Biology

Monosaccharides are polyhydroxy aldehydes or ketones; that is, they are molecules with more than one hydroxyl group (-OH), and a carbonyl group (C=O) either at the terminal carbon atom (aldose) or at the second carbon atom (ketose). The carbonyl group combines in aqueous solution with one hydroxyl group to form a cyclic compound (hemi-acetal or hemi-ketal). Monosaccharides are classified by the number of carbon atoms in the molecule; trioses have three, tetroses four, pentoses five, hexoses six, and heptoses seven.

Most contain five or six. The most important pentoses include xylose, found combined as xylan in woody materials; arabinose from coniferous trees; ribose, a component of ribonucleic acids and several vitamins; and deoxyribose, a component of deoxyribonucleic acid. Among the most important aldohexoses are glucose, mannose, and galactose; fructose is a ketohexose. Several derivatives of monosaccharides are important. Ascorbic acid (vitamin C) is derived from glucose.

Important sugar alcohols (alditols), formed by the reduction of (i. e. , addition of hydrogen to) a monosaccharide, include sorbitol (glucitol) from glucose and mannitol from mannose; both are used as sweetening agents. Glycosides derived from monosaccharides are widespread in nature, especially in plants. Amino sugars (i. e. , sugars in which one or two hydroxyl groups are replaced with an amino group, -NH2) occur as components of glycolipids and in the chitin of arthropods.

The most common naturally occurring monosaccharides are D-glucose, D-mannose, D-fructose, and D-galactose among the hexoses, and D-xylose and L-arabinose among the pentoses. In a special sense, D-ribose and 2-deoxy-D-ribose are ubiquitous because they form the carbohydrate component of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), respectively; these sugars are present in all cells as components of nucleic acids. Sources of some of the naturally occurring monosaccharides are listed in Table 2.

D-xylose, found in most plants in the form of a polysaccharide called xylan, is prepared from corncobs, cottonseed hulls, or straw by chemical breakdown of xylan. D-galactose, a common constituent of both oligosaccharides and polysaccharides, also occurs in carbohydrate-containing lipids, called glycolipids, which are found in the brain and other nervous tissues of most animals. Galactose is generally prepared by acid hydrolysis (breakdown involving water) of lactose, which is composed of galactose and glucose.

Since the biosynthesis of galactose in animals occurs through intermediate compounds derived directly from glucose, animals do not require galactose in the diet. In fact, in most human populations (Caucasoid peoples being the major exception) the majority of people do not retain the ability to manufacture the enzyme necessary to metabolize galactose after they reach the age of four, and many individuals possess a hereditary defect known as galactosemia and never have the ability to metabolize galactose.

D-glucose (from the Greek word glykys, meaning “sweet”), the naturally occurring form, is found in fruits, honey, blood, and, under abnormal conditions, in urine. It is also a constituent of the two most common naturally found disaccharides, sucrose and lactose, as well as the exclusive structural unit of the polysaccharides cellulose, starch, and glycogen. Generally, D-glucose is prepared from either potato starch or cornstarch. D-fructose, a ketohexose, is one of the constituents of the disaccharide sucrose and is also found in uncombined form in honey, apples, and tomatoes.

Fructose, generally considered the sweetest monosaccharide, is prepared by sucrose hydrolysis and is metabolized by man. Chemical reactions The reactions of the monosaccharides can be conveniently subdivided into those associated with the aldehydo or keto group and those associated with the hydroxyl groups. The relative ease with which sugars containing a free or potentially free aldehydo or keto group can be oxidized to form products has been known for a considerable time and once was the basis for the detection of these so-called reducing sugars in a variety of sources.

For many years, analyses of blood glucose and urinary glucose were carried out by a procedure involving the use of an alkaline copper compound. Because the reaction has undesirable features–extensive destruction of carbohydrate structure occurs, and the reaction is not very specific (i. e. , sugars other than glucose give similar results) and does not result in the formation of readily identifiable products–blood and urinary glucose now are analyzed by using the enzyme glucose oxidase, which catalyzes the oxidation of glucose to products that include hydrogen peroxide.

The hydrogen peroxide then is used to oxidize a dye present in the reaction mixture; the intensity of the colour is directly proportional to the amount of glucose initially present. The enzyme, glucose oxidase, is highly specific for -D-glucose. In another reaction, the aldehydo group of glucose reacts with alkaline iodine to form a class of compounds called aldonic acids. One important aldonic acid is ascorbic acid (vitamin C, see structure), an essential dietary component for man and guinea pigs.

The formation of similar acid derivatives does not occur with the keto sugars. Either the aldehydo or the keto group of a sugar may be reduced (i. e. , hydrogen added) to form an alcohol; compounds formed in this way are called alditols, or sugar alcohols. The product formed as a result of the reduction of the aldehydo carbon of D-glucose is called sorbitol (D-glucitol). D-glucitol also is formed when L-sorbose is reduced. The reduction of mannose results in mannitol, that of galactose in dulcitol.

Sugar alcohols that are of commercial importance include sorbitol (D-glucitol), which is commonly used as a sweetening agent, and D-mannitol, which is also used as a sweetener, particularly in chewing gums, because it has a limited water solubility and remains powdery and granular on long storage. Formation of glycosides The hydroxyl group that is attached to the anomeric carbon atom (i. e. , the carbon containing the aldehydo or keto group) of carbohydrates in solution has unusual reactivity, and derivatives, called glycosides, can be formed; glycosides formed from glucose are called glucosides.

It is not possible for equilibration between the – and -anomers of a glycoside in solution (i. e. , mutarotation) to occur. The reaction by which a glycoside is formed (see below) involves the hydroxyl group (-OH) of the anomeric carbon atom (numbered 1) of both and forms of D-glucose– and forms of D-glucose are shown in equilibrium in the reaction sequence–and the hydroxyl group of an alcohol (methyl alcohol in the reaction sequence); methyl -D-glucosides and -D-glucosides are formed as products, as is water.

Among the wide variety of naturally occurring glycosides are a number of plant pigments, particularly those red, violet, and blue in colour; these pigments are found in flowers and consist of a pigment molecule attached to a sugar molecule, frequently glucose. Plant indican (from Indigofera species), composed of glucose and the pigment indoxyl, was important in the preparation of indigo dye before synthetic dyes became prevalent. Of a number of heart-muscle stimulants that occur as glycosides, digitalis is still used.

Other naturally occurring glycosides include vanillin, which is found in the vanilla bean, and amygdalin (oil of bitter almonds); a variety of glycosides found in mustard have a sulfur atom at position 1 rather than oxygen. A number of important antibiotics are glycosides; the best known are streptomycin and erythromycin. Glucosides–i. e. , glycosides formed from glucose–in which the anomeric carbon atom (at position 1) has phosphoric acid linked to it, are extremely important biological compounds.

For example, -D-glucose-1-phosphate (see formula), is an intermediate product in the biosynthesis of cellulose, starch, and glycogen; similar glycosidic phosphate derivatives of other monosaccharides participate in the formation of naturally occurring glycosides and polysaccharides. The hydroxyl groups other than the one at the anomeric carbon atom can undergo a variety of reactions, several of which deserve mention.

Esterification, which consists of reacting the hydroxyl groups with an appropriate acidic compound, results in the formation of a class of compounds called sugar esters. Among the common ones are the sugar acetates, in which the acid is acetic acid. Esters of phosphoric acid and sulfuric acid are important biological compounds; glucose-6-phosphate, for example, plays a central role in the energy metabolism of most living cells, and D-ribulose 1,5-diphosphate is important in photosynthesis.

Formation of methyl ethers Treatment of a carbohydrate with methyl iodide or similar agents under appropriate conditions results in the formation of compounds in which the hydroxyl groups are converted to methyl groups (-CH3). Called methyl ethers, these compounds are employed in structural studies of oligosaccharides and polysaccharides because their formation does not break the bonds, called glycosidic bonds, that link adjacent monosaccharide units.

In the reaction sequence shown, a segment of a starch molecule, consisting of three glucose units, is indicated; the Haworth formulation used to represent one of the glucose units shows the locations of the glycosidic bonds and the -OH groups. When complete etherification of the starch molecule is carried out, using methyl iodide, methyl groups become attached to the glucose molecules at the three positions shown in the methylated segment of the starch molecule; note that the glycosidic bonds have not been broken by the reaction with methyl iodide.

When the methylated starch molecule then is broken down (hydrolyzed), hydroxyl groups are located at the positions in the molecule previously involved in linking one sugar molecule to another, and a methylated glucose, in this case named 2,3,6 tri-O-methyl-D-glucose, forms. The linkage positions (in the example, at carbon atoms 1 and 4; the carbon atoms are numbered in the structure of the methylated glucose), which are not methylated, in a complex carbohydrate can be established by analyzing the locations (in the example, at carbon atoms 2, 3, and 6) of the methyl groups in the monosaccharides.

This technique is useful in determining the structural details of polysaccharides, particularly since the various methylated sugars are easily separated by techniques involving gas chromatography, in which a moving gas stream carries a mixture through a column of a stationary liquid or solid, the components thus being resolved. When the terminal group (CH2OH) of a monosaccharide is oxidized chemically or biologically, a product called a uronic acid is formed.

Glycosides that are derived from D-glucuronic acid (the uronic acid formed from D-glucose) and fatty substances called steroids appear in the urine of animals as normal metabolic products; in addition, foreign toxic substances are frequently converted in the liver to glucuronides before excretion in the urine. D-glucuronic acid also is a major component of connective tissue polysaccharides, and D-galacturonic acid and D-mannuronic acid, formed from D-galactose and D-mannose, respectively, are found in several plant sources.

Other compounds formed from monosaccharides include those in which one hydroxyl group, usually at the carbon at position 2 (see formulas for D-glucosamine and D-galactosamine), is replaced by an amino group (-NH2); these compounds, called amino sugars, are widely distributed in nature. The two most important ones are glucosamine (2-amino-2-deoxy-D-glucose) and galactosamine (2-amino-2-deoxy-D-galactose). Neither amino sugar is found in the uncombined form. Both occur in animals as components of glycolipids or polysaccharides; e. g. , the primary structural polysaccharide (chitin) of insect outer skeletons and various blood-group substances.

In a number of naturally occurring sugars, known as deoxy sugars, the hydroxyl group at a particular position is replaced by a hydrogen atom. By far the most important representative is 2-deoxy-D-ribose (see formula), the pentose sugar found in deoxyribonucleic acid (DNA); the hydroxyl group at the carbon atom at position 2 has been replaced by a hydrogen atom. Other naturally occurring deoxy sugars are hexoses, of which L-rhamnose (6-deoxy-L-mannose) and L-fucose (6-deoxy-L-galactose) are the most common; the latter, for example, is present in the carbohydrate portion of blood-group substances and in red-blood-cell membranes.

Disaccharides and oligosaccharides Disaccharides are a specialized type of glycoside in which the anomeric hydroxyl group of one sugar has combined with the hydroxyl group of a second sugar with the elimination of the elements of water. Although an enormous number of disaccharide structures are possible, only a limited number are of commercial or biological significance. Sucrose and trehalose Sucrose, or common table sugar, has a world production amounting to well over 10,000,000 tons annually.

The unusual type of linkage between the two anomeric hydroxyl groups of glucose and fructose (see formula, in which the asterisk indicates anomeric carbon atom) means that neither a free aldehydo group (on the glucose moiety) nor a free keto group (on the fructose moiety) is available to react unless the linkage between the monosaccharides is destroyed; for this reason, sucrose is known as a nonreducing sugar. Sucrose solutions do not exhibit mutarotation, which involves formation of an asymmetrical centre at the aldehydo or keto group.

If the linkage between the monosaccharides composing sucrose is broken, the optical rotation value of sucrose changes from positive to negative; the new value reflects the composite rotation values for D-glucose, which is dextrorotatory (+52), and D-fructose, which is levorotatory (-92). The change in the sign of optical rotation from positive to negative is the reason sucrose is sometimes called invert sugar. The commercial preparation of sucrose takes advantage of the alkaline stability of the sugar, and a variety of impurities are removed from crude sugarcane extracts by treatment with alkali.

After this step, syrup preparations are crystallized to form table sugar. Successive “crops” of sucrose crystals are “harvested,” and the later ones are known as brown sugar. The residual syrupy material is called either cane final molasses or blackstrap molasses; both are used in the preparation of antibiotics, as sweetening agents, and in the production of alcohol by yeast fermentation. Sucrose is formed following photosynthesis in plants by a reaction in which sucrose phosphate first is formed. The disaccharide trehalose is similar in many respects to sucrose but is much less widely distributed.

It is composed of two molecules of -D-glucose and is also a nonreducing sugar. Trehalose is present in young mushrooms and in the resurrection plant (Selaginella); it is of considerable biological interest because it is also found in the circulating fluid (hemolymph) of many insects. Since trehalose can be converted to a glucose phosphate compound by an enzyme-catalyzed reaction that does not require energy, its function in hemolymph may be to provide an immediate energy source, a role similar to that of the carbohydrate storage forms (i. e. , glycogen) found in higher animals.

The autonomic nervous system is made up of two divisions. There are many differences between these divisions. First of all there are anatomical and physiological differences. The parasympathetic division of the autonomic system origin is in the craniosacral outflow, the brain stem nuclei of cranial nerves III, VII, IX, and X; and spinal cord segments S2-S4. The sympathetic division on the other hand is much more complex than the parasympathetic and is originated in the thoracolumbar outflow. Also, in the lateral horn of gray matter of the spinal cord segments of thoracic 1 to lumbar 2.

Another important physiological difference is the location of ganglia in each division. Ganglia of the parasympathetic division are in intramural or close to the visceral organ served. The sympathetic ganglia are located with in a few centimeters of the central nervous system. They are also alongside the vertebral column and anterior to the vertebral column. The relative length of preganglionic and postganglionic fibers in the parasympathetic and sympathetic divisions is as such. The parasympathetic have long preganglionic and short postganglionic.

The sympathetic are just the opposite, short preganglionic and long postganglionic. There is no rami communication in the parasympathetic division, while the sympathetic division has gray and white rami communication. The functional goal of the parasympathetic division is maintenance functions, to conserve and store energy. The sympathetic divisions goal is to provide the body to cope with emergencies and intense muscular activity. There are many effects of the parasympathetic and sympathetic divisions on various organs.

The constricting of uscles and eye pupils stimulates the iris of the eye by the parasympathetic system. The sympathetic effects are the stimualtes of dilator muscles and dilate the eye pupils. The parasympathetic effects of the cilliary muscle of the eye are to stimulate muscles, which result in the bulging of the lens for accommodation and close vision. There are no effects for the sympathetic division. The nasal lacrimal, salivary, gastric, and pancreas glands are effected by the parasympathetic and sympathetic systems.

The parasympathetic ivision stimulates secretory activity, where the sympathetic division inhibits secretory activity and causes vasoconstruction of blood vessels supplying the glands. There is no parasympathetic effect on sweat galnds, the adrenal medulla, or the arrector pili muscles. There are sympathetic effects though. The glands are inhibited by secretory activity causing vasoconstruction of blood vessels supplying the glands. The sweat glands are stimulated copious sweating. The arrector pili muscles are stimulated to contract and produce goosebumps.

The arasympathetic division decreases the rate of the heart and slows it down. The sympathetic division increases the rate and force of the heart. The bladder in both divisions is opposite once again. In the parasympathetic of the bladder, the contraction of smooth muscle and the relaxation in the sympathetic division. The parasympathetic constricts for the bronchioles of the lungs, where the bronchioles are dilated in the sympathetic. The livers sympathetic effect is in epinephrine stimulus of the liver to release glucose to the blood. There is o parasympathetic effect of the liver.

In the parasympathetic division the gallbladder contracts to expel bile. In the sympathetic division the gallbladder is relaxed. The parasympathetic division causes the penis and vagina to vasodilateor erect. The sympathetic division causes the penis to ejaculate and the vagina to contract. There is little or no effect of the blood vessels in the parasympathetic division. The sympathetic division constricts most vessels and increases the blood pressure. It also constricts vessels of abdominal viscera nd skin to divert blood to muscles, brain, and heart when necessary.

The cellular metabolism of the sympathetic division is to increase coagulation. Sympathetic effects; adipose tissue by lipolysis, and mental activity by increasing ones alertness. I found the assignment a little different then most papers I have written do to one fact. I found that I could not put what the book said into my own words. I dont have a wide anatomical vocabulary, so I found that I had to copy a lot of what the book said. I am sure this is similar to some students in the class.

If you have had a can of soft drink, ate a fruit, or took some head ache medicine this morning – then it’s very likely you have used a genetically enhanced product. Genetics is a part of biotechnology that manipulates biological organisms to make products that benefit humankind. Biotechnology is essential in our life, but there are some concerns regarding its safety. Although, biotechnology may pose some danger it is proving to be very beneficial to humankind. The first applications of biotechnology occurred approximately around 5000 BC. Back then people used simple breeding methods.

Chains of plants or animals were crossed to produce greater genetic variety. The hybridized offspring then were selectively bred to produce the desired traits. For example, for about 7000 years, corn has been selectively bred for increased kernel size and additional nutrition value. Also, through selective breeding, cattle and pigs have become the major sources of animal foods for human (Encarta 99). The modern era of biotechnology started in 1953 when British biophysicist Francis Crick and American biochemist James Watson presented their double-stranded model of DNA.

DNA is an extensive, chain-like structure made up of nucleotides, and in a way it looks like a twisted rope ladder (Drlica 27). In 1960 Swiss microbiologist Werner Arber had discovered restriction enzymes. This special kind of enzymes can cut DNA of an organism at precise points. In 1973 American scientists Stanley Cohen and Herbert Boyer removed a specific gene from one bacterium and inserted it into another using restriction enzymes. This achievement served as foundation to recombinant DNA technology, which is commonly called genetic engineering.

Recombinant DNA technology is a transfer of a specifically coded gene of one organism into bacteria. Further, the host bacteria serve as a biologic factory by reproducing the transferred gene. Today biotechnology’s applications are used in a variety of areas. It’s used in waste management for creation of biodegradable materials, in agriculture for higher yields and quality, in medicine for production of advanced pharmaceuticals, cloning tissues and curing genetic diseases. However there is a down side to genetic engineering. It deals with dangerous bacteria which could escape the boundaries of a lab and possibly cause epidemics.

Moreover, if a transgenic organism escapes, it could eliminate a range of species and thus disrupt natural balance. Since biotechnology is a necessity, some government guidelines were established for strict regulation of recombinant DNA experiments (Encarta 99). Agriculture is the largest business in the world, with assets of approximately $900 billion and about 15 million employees. Back in the 80’s, there was a concern, based on population growth rates, that by the turn of the century traditional agriculture would be in a serious trouble (Hanson 68).

But due to the revolutionary development of biotechnology during last couple of decades agriculture has drastically advanced. Sensational achievements were made in both plant cultivation and animal husbandry. The modification of plants has become one of the most important aspects in agriculture. Increased crop yields can be achieved through the increase of land, or increased yield per tract. Land is expensive and should be used efficiently, to do so – large quantities of fertilizer, herbicides, pesticides and frequent irrigation may be necessary.

Due to the increase in petroleum cost – prices for nitrogen fertilizers continuously rise. Herbicides and pesticides are considered to be hazardous and very costly materials. Moreover, recurrent irrigation gradually leads to serious damage of the soil due to the salt accumulation. Eventually, increased amounts of salt in the soil result in large losses of crops (Hanson 69). Biotechnology can incorporate genes that are resistant to environmental stress, viruses, and insects. Such modified plants will be resistant to the same factors as the incorporated gene.

Crop plants could be genetically engineered to manufacture functional insecticides so that they are immanently tolerant to insects. No hazardous and costly pesticides are needed for such plants resulting in very low crop maintenance costs. Moreover, biological insecticides are highly specific for a range of insects and considered to be harmless to humans and other higher animals (Glick and Pasternak 341). Plant viruses very often attack crops and cause significant damage and loss of crops.

Recombinant DNA technology offers a few ways to obtain natural virus resistance: viral transmission can be blocked, development of the virus can be blocked, or viral symptoms can be bypassed or resisted (Glick and Pasternak 345). Biotechnology also contributes to the development of plants with higher tolerance to environmental changes. Plants cannot avoid hazardous environmental conditions such as heat, drought, and UV radiation, so they have developed physiological ways to deal with those stresses. One of the undesirable effects of physiological stress is production of oxygen radicals.

Trough the use of recombinant DNA technology some plants are given the ability to tolerate high levels of oxygen radicals, these plants are capable of withstanding a various range of environmental stress (Glick and Pasternak 350). Another important area of biotechnology is improvement of livestock. Many generations of selective matings are required to improve livestock and other domesticated animals genetically for traits such as milk yield, wool characteristics, rate of weight gain, and egg laying frequency. At each successive generation, animals with superior performance characteristics are used as breeding stock.

Eventually, high production animals are developed as more or less pure breeding lines. This combination of mating and selection, although time-consuming and costly, has been exceptionally successful. Today almost all aspects of the biological basis of livestock production can be attributed to this process. However, once an effective genetic line has been established, it becomes difficult to introduce new genetic traits by selective breeding methods (Glick and Pasternak 359). Until recently, the only way to enhance genetic properties of domesticated animals was selective breeding.

However, research in new areas of biotechnology lead to the development of new technologies and almost completely replaced traditional methodologies. Using recombinant DNA technology, scientists are able to insert a specific cloned gene in to the nucleus of fertilized egg of a higher organism. Then the fertilized egg is implanted into a receptive female. Most of the offspring derived from the implanted eggs will have the cloned gene in all their cells. The animals with the transgenic gene in their germ line are bred to establish new superior genetic lines.

For example if the injected gene stimulates growth, the animals that received the gene would grow faster and require less food. Even if consumption of food was cut down by only a few percent – it still would have a profound effect on lowering the cost of production and the price of final product (Glick and Pasternak 361). Another area that benefits from biotechnology is medicine. This particular sector of biotechnology had risen from about $6 billion share of global market in 1983 (Hanson 66) to about $100 billion in 1997 (“The Biotech Boom” 89).

McDonald states that “today, there are more than 2,200 drugs that are in development and 234 awaiting approval from FDA” (91). The primary reasons for such rapid development are millions of deaths each year caused by disease, viruses, and genetic disorders. Biotechnology is widely used in pharmacy to create more efficient and less expensive drugs. Recombinant DNA technology is used for production of specific enzymes, which enhance the rate of production of particular range of antibodies in the organism (Hanson 67).

Antibiotics produced using such technology have very specific effects and cause fewer side effects. Also, using similar methods a range of vaccines can be created. Currently, scientists are working on vaccines for fatal illnesses such as AIDS, hepatitis, malaria, flu, and even some forms of cancer. Shrof expects that in the near future vaccines will come in more convenient ways “some will come in the form of mouthwash; others will be swallowed in time-release capsules, avoiding the need for boosters. ” (57).

Some genetically altered foods that will convey antigens against some disease are expected to be available in about five years (“Miracle Vaccines” 57,67). Genetic disease could be treated through the use of genetic engineering. Defective genes in an organism cause genetic disorders. If a defective gene could be identified and located in a particular group of cells – it could be replaced with a functional one. The transgenic cells are then planted into the organism, resulting in a cure of the disorder (Jackson and Stich 64,65).

Cloning is a relatively new sector of biotechnology, but it promises answers to very important problems related to surgery. Tissues and organs could be cloned for surgical purposes. If scientists could isolate stem cells, (stem cells have a potential to grow into any kind of tissue or organ) and then direct their development, they would be able to create any kind of a tissue, organ or even a whole part of a body (“On the Horizon” 89). In a way, biotechnology is just like one of its products – for all the positive effects of biotechnology there are some possible side effects.

The double-stranded molecule of DNA, originally honored for its intelligibility, in present society portraits a double-sided sword, which could be employed as an agent of death as well as an agent of life (“All for the Good” 91). There are some concerns that genetic engineering could pose some serious danger to earth inhabitants. Nobody knows what ecological hazards could be caused by novel transgenic organisms (“DNA Disasters? ” 80). The opposition of genetic engineering says that – the science is very young and needs a lot more research.

The majority of recombinant DNA experiments use E. li bacteria as a host for production of transgenic proteins. E. coli could be harmful to human beings and other species. Although the experiments are conducted in secure, contained facilities, there is a chance that some of bacteria could escape the boundaries of such laboratory. Escaped bacteria then could find an environment for replication and could spread at a fast pace. Some species could be infected and transmit the bacteria to others, thus causing global epidemics (Jackson and Stich 99-113). Moreover, genetic engineering enables the scientists to combine genetic materials of unrelated organisms.

Such recombinant events across species have never been fond in nature. There is a chance that such hybrid organisms could escape from a laboratory. The escaped transgenic organisms could eliminate a range of species, and disrupt the natural balance. Not to mention that such organisms could abolish the human kind. However, scientists tend to think that there is a little chance of such happening (Jackson and Stich 127). Hanson says that “the primary objective of genetic engineering is to control the genetic structures of many individual life forms which inhabit this planet, including humans, for their own benefit” (21).

However, some individual scientists may have different goals. Indeed, some scientists may participate in illegal activities in order to achieve large financial rewards. There is a concern that some genetic project information could be sold to a group of terrorists or such and then used for development of biological weapons. Use of biological weapons could wipe out vast portion of specific species in a particular region or even the whole planet. There are some convincing reasons for biotechnology to be carefully regulated.

In 1976, the National Institutes of Health (NIH) established a recombinant DNA Advisory Committee (RAC). RAC is responsible for creating guidelines governing recombinant DNA experiments. All the institutions, companies or individuals working in the field of genetics must obey those guidelines. By the end of 1981, after reviewing the record carefully, RAC drew the conclusion that some of its requirements could be loosened up because safety of new technology was established (Hanson 80). Food and Drug Administration (FDA) has very high standards for proof of safety and efficacy.

However, FDA has taken a constructive attitude in making the products of biotechnology quickly and safely available to the public. FDA does not require any unnecessary studies and provides the companies with technical assistance while taking the product through the approval system. Today, there are 234 new drugs awaiting approval from FDA (Hanson 82). Innovation cannot exist without a strong patent system. If there were no patent system, the invention of one company could become available to other companies that did not incur high research and development cost.

Without the potential for protecting company’s developments, there would be a little chance to raise enough capital for growth and support of the company during the period while the products go through regulatory approval process. The patent system also contributes to a development of stronger economy by producing more competition. Under patent protection a new company can compete against larger, older and more entrenched companies. This, in turn, eliminates the possibility of monopoly and results in faster development and lower prices of the products (Encarta 99).

On one hand, there are some concerns regarding safety of biotechnological experiments. However, over the years biotechnology has proved to be exceptionally safe. On the other hand, there is a strong need for more efficient agriculture and higher achievements in medical field. Biotechnology has also proved to be extremely productive, and innovative coming up with the answers for the problems mentioned above. In conclusion, if the 20th century was the century of physics, the 21st century should be the century of biology.

Corynebacteria are Gram-positive, aerobic, nonmotile, rod-shaped bacteria related to the Actinomycetes. They do not form spores or branch as do the actinomycetes, but they have the characteristic of forming irregular shaped, club-shaped or V-shaped arrangements in normal growth. They undergo snapping movements just after cell division which brings them into characteristic arrangements resembling Chinese letters. The genus Corynebacterium consists of a diverse group of bacteria including animal and plant pathogens, as well as saprophytes.

Some corynebacteria are part f the normal flora of humans, finding a suitable niche in virtually every anatomic site. The best known and most widely studied species is Corynebacterium diphtheriae, the causal agent of the disease diphtheria. History and Background No bacterial disease of humans has been as successfully studied as diphtheria. The etiology, mode of transmission, pathogenic mechanism and molecular basis of exotoxin structure, function, and action have been clearly established. Consequently, highly effective methods of treatment and prevention of diphtheria have been developed.

The study of Corynebacterium diphtheriae traces closely the development of medical , immunology and molecular biology. Many contributions to these fields, as well as to our understanding of host-bacterial interactions, have been made studying diphtheria and the diphtheria toxin. Hippocrates provided the first clinical description of diphtheria in the 4th century B. C. There are also references to the disease in ancient Syria and Egypt. In the 17th century, murderous epidemics of diphtheria swept Europe; in Spain “El garatillo” (the strangler”), in Italy and Sicily, “the gullet disease”.

In the 18th century, the disease reached the American colonies and reached epidemic proportions in 1735. Often, whole families died of the disease in a few weeks. The bacterium that caused diphtheria was first described by Klebs in 1883, and was cultivated by Loeffler in 1884, who applied Koch’s postulates and properly identified Corynebacterium diphtheriae as the agent of the disease.

In 1884, Loeffler concluded that C. diphtheriae produced a soluble toxin, and thereby provided the first description of a bacterial exotoxin. In 1888, Roux and Yersin demonstrated the presence of the toxin in the cell-free ulture fluid of C. iphtheriae which, when injected into suitable lab animals, caused the systemic manifestation of diphtheria. Two years later, von Behring and Kitasato succeeded in immunizing guinea pigs with a heat-attenuated form of the toxin and demonstrated that the sera of immunized animals contained an antitoxin capable of protecting other susceptible animals against the disease.

This modified toxin was suitable for immunizing animals to obtain antitoxin but was found to cause severe local reactions in humans and could not be used as a vaccine. In 1909, Theobald Smith, in the U. S. emonstrated that diphtheria toxin neutralized by antitoxin (forming a Toxin-Anti-Toxin complex, TAT) remained immunogenic and eliminated local reactions seen in the modified toxin.

For some years, beginning about 1910, TAT was used for active immunization against diphtheria. TAT had two undesirable characteristics as a vaccine. First, the toxin used was highly toxic, and the quantity injected could result in a fatal toxemia unless the toxin was fully neutralized by antitoxin. Second, the antitoxin mixture was horse serum, the components of which tended to be allergenic and to sensitize individuals to the serum.

In 1913, Schick designed a skin test as a means of determining susceptibility or immunity to diphtheria in humans. Diphtheria toxin will cause an inflammatory reaction when very small amounts are injected intracutaneously. The Schick Test involves injecting a very small dose of the toxin under the skin of the forearm and evaluating the injection site after 48 hours. A positive test (inflammatory reaction) indicates susceptibility (nonimmunity). A negative test (no reaction) indicates immunity (antibody neutralizes toxin).

In 1929, Ramon demonstrated the conversion of diphtheria toxin to its nontoxic, ut antigenic, equivalent (toxoid) by using formaldehyde. He provided humanity with one of the safest and surest vaccines of all time-the diphtheria toxoid. In 1951, Freeman made the remarkable discovery that pathogenic (toxigenic) strains of C. diphtheriae are lysogenic, (i. e. , are infected by a temperate B phage), while non lysogenized strains are avirulent. Subsequently, it was shown that the gene for toxin production is located on the DNA of the B phage.

In the early 1960s, Pappenheimer and his group at Harvard conducted experiments on the mechanism of a action of the diphtheria toxin. They studied the effects of the toxin in HeLa cell cultures and in cell-free systems, and concluded that the toxin inhibited protein synthesis by blocking the transfer of amino acids from tRNA to the growing polypeptide chain on the ribosome. They found that this action of the toxin could be neutralized by prior treatment with diphtheria antitoxin. Subsequently, the exact mechanism of action of the toxin was shown, and the toxin has become a classic model of a bacterial exotoxin.

Human Disease Diphtheria is a rapidly developing, acute, febrile infection which involves both local and systemic pathology. A local lesion develops in the upper respiratory tract and involves necrotic injury to epithelial cells. As a result of this injury, blood plasma leaks into the area and a fibrin network forms which is interlaced with with rapidly-growing C. diphtheriae cells. This membranous network covers over the site of the local lesion and is referred to as the pseudomembrane. The diphtheria bacilli do not tend to invade tissues below or away from the surface epithelial cells at the site of the local lesion.

At this site they produce the toxin that is absorbed and disseminated through lymph channels and lood to the susceptible tissues of the body. Degenerative changes in these tissues, which include heart, muscle, peripheral nerves, adrenals, kidneys, liver and spleen, result in the systemic pathology of the disease. In parts of the world where diphtheria still occurs, it is primarily a disease of children, and most individuals who survive infancy and childhood have acquired immunity to diphtheria. In earlier times, when nonimmune populations (i. e. , Native Americans) were exposed to the disease, people of all ages were infected and killed.

Every fall, homeowners have the same problem: dead leaves. Trees shed leaves and taint once perfected lawns. To get rid of these leaves, people rake the leaves and assemble them into large piles that trucks come and remove. If these piles are left long enough, they will heat up. On a cold day, steam can be seen rising from these piles of leaves. But why does it do this? Decomposition is the breaking down of a substance into parts that it was made of. Microorganisms break down organic matter while composting and making carbon dioxide, water, heat, and humus.

Composting usually has three phases: 1) the mesophilic (moderate temperature) stage which lasts two days, 2) the thermophilic (high temperature) stage which lasts for four to six days, and 3) the cooling down, maturing phase, which can last up to several months (Columbia University Press, 2000. ) Mesophilic microorganisms carry out stage one. The mesophilic microorganisms break down the stable, readily degradable compounds. The heat they create makes the compost temperature rise quickly. Stage two (the high temperatures) accelerates the breakdown of proteins, fats, and complex carbohydrates, at temperatures of 55 degrees and higher.

Many microorganisms that are human or plant pathogens are destroyed. Little holes are necessary to aerate this stage. Stage three has the supply of high-energy compounds that become exhausted. The compost temperature gradually decreases and mesophilic microorganisms take over for, the final phase of “curing” (maturation of remaining organic matter (Southwestern, 2003). ) There are three main gases in compost piles: carbon, nitrogen and oxygen. Carbon provides the energy source and is the “building block” that is 50% of mass microbial cells. Brown and woody materials are very high in carbon.

Carbon is more readily available for microbial use if an object has a large surface area. Nitrogen is an important component of the proteins, nucleic acid, amino acids, enzymes and co-entyns necessary for cell growth and function. Any materials that are green and moist are high in nitrogen. The nitrogen cycle is the continuous movement of nitrogen from the atmosphere, to plants, and back to the atmosphere (or directly into plants) again. Oxygen is essential for a compost pile to work. As microorganisms oxidize carbon for energy, oxygen is used up and carbon dioxide is produced.

Without enough oxygen, the process will become anaerobic and produce bad smells. Oxygen concentrations greater than 10% are considered best for maintaining aerobic composting. Some compost systems can be kept up enough oxygen passively (through natural diffusion and convention) and some systems require active aeration (Michigan Sate University, 2000. ) The temperature at any time depends on how much heat is being produced by microorganisms. The temperature is balanced by how much heat is lost through conduction, convection, and radiation.

Conduction is a medium for heat and electricity and is why the edges of a compost pile aren’t as hot as the middle. The heat spreads from the middle and fades out by the edges. Convection is the transfer of heat through the air. When the compost gets hot, the heat rises very slowly. Radiation is electromagnetic waves that carry out the heat of the pile. The warmth made in a compost pile radiates out into the cooler surrounding air. The smaller the pile, the greater the surface area-to-volume ratio and therefore the larger the degree of heat loss to conduction and radiation.

Insulation helps to reduce these losses (Raloff, 1993. ) There are five main microorganisms that live in a compost pile. They are bacteria, actinomycetes, fungi, protozoa, and rotifers. Bacteria are the smallest living organisms and the most plentiful in compost (they take up 80-90% of the billions of microorganisms found in a gram of compost. ) Bacteria use many kinds of enzymes to chemically break down organic materials. Mesophilic bacteria have forms that can be found in topsoil. Actinomicetes are another essential microorganism found in compost.

They play an important role in degrading complex organisms such as cellulous, lignim, chitin, and proteins. Actinomicetes’ enzymes enable them to chemically break down tough debris, such as woody stems, bark, or newspaper. Some species of Actinomicetes appear during the thermophilic phase, while others become important during the cooler curing stage. Fungi are more visible microorganisms and when in a group, can become very big. Fungi break down tough debris, letting bacteria continue the decomposition process after most of the cellous has been exhausted.

Fungi attack organic residues that are too dry, acidic, or low in nitrogen for bacterial decomposition. Fungal species are abundant during the mesophilic and thermophilic phases. Most fungi live in the outer layer of compost when temperatures are high. Protozoa are one-celled microscopic animals found in water droplets in compost. They contain their food from organic material in the same way as bacteria. Protozoa eat bacteria and fungi. Rotfiers are microscopic many-celled organisms found in films of water in the compound.

They feed on organic matter and also ingest bacteria and fungi (Michigan Sate University, 2000. ) Compost piles can be used as organic fertilizers that can help prevent pollution. They provide minerals and nutrients, which makes for rich mulch. Mulch is spread on the ground to protect the roots of plants from extreme temperature changes and moisture. Also, compost in mulch form enriches the soil (Merriam-Webster, 1998. ) An experiment was conducted with livestock manure, which was carried out by Holder Hack of the Agriculture Department’s Biosciences Research Laboratory in Fargo, N. D. Livestock produce large amounts of estrogen and testosterone, hormones that can harm crops and wildlife when farmers use manure as fertilizer.

Manure from egg-laying chickens was collected and mixed with hay, straw, decomposing leaves, and some starter compost. The manures concentrations of testosterone and estrogen decreased after decomposition. The experiment concluded that farmers could clear chicken manure of almost all harmful hormones by composting the wastes (Raloff, 2001. )

Clover, growth rate, inoculation with Nitrogen fixing bacteria in Nitrogen deficient conditions Nitrogen Fixation was proved to increase the growth of clover plants over a ten-week experiment in Nitrogen deficient conditions. The Hypothesis was proved correct with no difficulties encountered. Nitrogen is approximately 78% (volume) of dry air. It is present in the protoplasm of living matter and the compounds contained in Nitrogen (Nitric Acid, Explosives, Cyanides, Fertilisers and Protein) are necessary to the continuation of life.

Nitrogen is an essential constituent of Amino Acids that form Protein, which builds protoplasm. Although Nitrogen is about 78% (volume) of dry air this gaseous Nitrogen cant be used by animals or plants. The Nitrogen must be Fixed and turned into compounds such as Ammonia or Nitrates, which can be used. This is where Nitrogen Fixation comes in. Nitrogen Fixation is the term to describe the reduction of atmospheric Nitrogen to Ammonia. Nitrogen Fixing bacteria live in the roots of Leguminous plants like beans peas and clover.

The bacteria enter the plants through its root hairs and cause cells (cortical) of the root to proliferate which causes swelling called a Root Nodule. Vascular strands connect the nodule with vascular tissues in the main root. Bacteria rapidly multiply in the cells, fixing atmospheric Nitrogen which is then built up into Amino Acids and Proteins. The Amino Acid is then taken in by the plant to form plant tissue. There are two main types of Nitrogen fixing bacteria, those that live free in the soil and those that live enclosed in the root nodules of leguminous plants.

The free-living bacteria are species of Clostridium and Azotobacter. The se species are generally present in agriculture soils and use energy from decaying matter in the soil to fuel cell processes. The bacteria that live in the root nodules of leguminous plants are of the genus Rhizobium. Rhizobia can be found free living in the soil but cant fix Nitrogen in this state and in turn the legume root cannot fix Nitrogen without Rhizobia. This is not the only way Nitrogen can be fixed.

A certain amount of Nitrogen can be fixed by some blue-green algae and lightening but the soil bacteria previously mentioned perform the bulk of Nitrogen fixation. With all this in mind I have come up with the hypothesis: Clover seeds innoculated with Nitrogen Fixing bacteria will grow better than uninnoculated clover seeds when both grown in Nitrogen deficient conditions. Test Tubes containing Nitrogen Deficient Agar Roots of Clover plant containing pink nodules The clover seeds were purchased from a nursery and placed into a beaker containing bleach (2% Hyper Chloride) for five minutes to steralise them.

The nodules were then rinsed in boiled, cooled distilled water. This process was repeated three times. The nodules were then place into test tubes containing Nitrogen deficient Agar using a steralised scalpel to transfer them. Rolled cotton plugs were then placed into the test tube and placed on a cool, well lit window. Pink nodules were picked from the root of a clover plant and placed into a beaker containing bleach (2% Hyper Chloride) for five minutes to steralise them. The nodules were then rinsed in boiled, cooled distilled water.

This process was repeated three times. The nodules were then transferred to a clean glass slide using steralised scalpels. The nodules were then squashed, also using a steralised scalpel, in a large drop of water. Steralised clover seeds were then transferred using a steralised scalpel into the squashed nodule mix and placed into test tubes containing Nitrogen Deficient Agar. The test tubes were then labelled and placed on a cool well-lit window with rolled cotton plugs in them.

Control Group – Mean stem length of clover plant over number of weeks 1 2 3 4 5 6 7 8 9 10 . 751. 622. 01 3. 113. 563. 843. 483. 35 3. 31 3. 3 Experimental Group Mean stem length of clover plant over number of weeks 2 3 4 5 6 7 8 9 10 . 55 1. 21. 75 2. 43. 483. 92 4. 24. 785. 366. 25 After Five weeks the Experimental Group looked a lot healthier. Its leaves were larger, more numerous and rich in colour. The Control Groups leaves were much paler and less numerous.

From these results you can see that the hypothesis: Clover seeds innoculated with Nitrogen Fixing bacteria will grow better than uninnoculated seeds when both grown in Nitrogen deficient conditions, was proved. In the first five weeks the control group grew slightly better than the experimental, but the experimental group looked healthier. It is after the sixth week that we see a dramatic difference in the two groups. The control group starts to decrease in size then level out and reach its maximum length.

The experimental group increases rapidly to almost double the height of the control group. From these results we cannot see the maximum height of the experimental group, although given more time we would be able to see this. Although the Hypothesis was proved, how can we make this experiment better? I think that if the squashed nodules were added to the clover seeds at the fifth week the development of the plant would be even more significant than before. The squashed nodules should be added at the fifth week just before the plant reaches its peak.

That way it gives the added nodules a week to start working before hand. The clover plant may grow to be bigger and better than the experimental plant, which could be beneficial. We know that Nitrogen fixation improves legume plant quality but can it improve the quality of more useful plants such as crops? Alan H. Gibson from the CSRIO Division of Plant Industry believes not. my colleagues and I believe this to be most unlikely due to the stringency of the conditions necessary for these genes to be expressed.

The association between Legume Rhizobium is very specific, as I mentioned before Rhizobium cannot fix Nitrogen without legumes and vice versa nor can it fix Nitrogen with soybeans or lupins because it cant nodulate with other species. I believe that once this hurdle is over come scientists will be able to produce Nitrogen Fixation with useful crops so that our productivity is greater. In the future we may find out why the association between Legume Rhizobium is so complex and why they only nodulate with each other but for now we will just have to keep on experimenting to get it right.

It was in 1886 that the German pharmacologist, Louis Lewin, published the first systematic study of the cactus, to which his own name was subsequently given. Anhalonium lewinii was new to science. To primitive religion and the Indians of Mexico and the American Southwest it was a friend of immemorially long standing. Indeed, it was much more than a friend. In the words of one of the early Spanish visitors to the New World, “they eat a root which they call peyote, and which they venerate as though it were a deity. ”

Why they should have venerated it as a deity became apparent when such eminent psychologists as Jaensch, Havelock Ellis and Weir Mitchell began their experiments with mescalin, the active principle of peyote. True, they stopped short at a point well this side of idolatry; but all concurred in assigning to mescalin a position among drugs of unique distinction. Administered in suitable doses, it changes the quality of consciousness more profoundly and yet is less toxic than any other substance in the pharmacologist’s repertory. Mescalin research has been going on sporadically ever since the days of Lewin and Havelock Ellis.

Chemists have not merely isolated the alkaloid; they have learned how to synthesize it, so that the supply no longer depends on the sparse and intermittent crop of a desert cactus. Alienists have dosed themselves with mescalin in the hope thereby of coming to a better, a first-hand, understanding of their patients’ mental processes. Working unfortunately upon too few subjects within too narrow a range of circumstances, psychologists have observed and catalogued some of the drug’s more striking effects. Neurologists and physiologists have found out something about the mechanism of its action upon the central nervous system.

And at least one Professional philosopher has taken mescalin for the light it may throw on such ancient, unsolved riddles as the place of mind in nature and the relationship between brain and consciousness. There matters rested until, two or three years ago, a new and perhaps highly significant fact was observed. * Actually the fact had been staring everyone in the face for several decades; but nobody, as it happened, had noticed it until a Young English psychiatrist, at present working in Canada, was struck by the close similarity, in chemical composition, between mescalin and adrenalin.

Further research revealed that lysergic acid, an extremely potent hallucinogen derived from ergot, has a structural biochemical relationship to the others. Then came the discovery that adrenochrome, which is a product of the decomposition of adrenalin, can produce many of the symptoms observed in mescalin intoxication. But adrenochrome probably occurs spontaneously in the human body. In other words, each one of us may be capable of manufacturing a chemical, minute doses of which are known to cause Profound changes in consciousness.

Certain of these changes are similar to those which occur in that most characteristic plague of the twentieth century, schizophrenia. Is the mental disorder due to a chemical disorder? And is the chemical disorder due, in its turn, to psychological distresses affecting the adrenals? It would be rash and premature to affirm it. The most we can say is that some kind of a prima facie case has been made out. Meanwhile the clue is being systematically followed, the sleuths–biochemists , psychiatrists, psychologists–are on the trail.

By a series of, for me, extremely fortunate circumstances I found myself, in the spring of 1953, squarely athwart that trail. One of the sleuths had come on business to California. In spite of seventy years of mescalin research, the psychological material at his disposal was still absurdly inadequate, and he was anxious to add to it. I was on the spot and willing, indeed eager, to be a guinea pig. Thus it came about that, one bright May morning, I swallowed four-tenths of a gram of mescalin dissolved in half a glass of water and sat down to wait for the results.

We live together, we act on, and react to, one another; but always and in all circumstances we are by ourselves. The martyrs go hand in hand into the arena; they are crucified alone. Embraced, the lovers desperately try to fuse their insulated ecstasies into a single self-transcendence; in vain. By its very nature every embodied spirit is doomed to suffer and enjoy in solitude. Sensations, feelings, insights, fancies–all these are private and, ex- cept through symbols and at second hand, incommunicable.

We can pool information about experiences, but never the experiences themselves. From family to nation, every human group is a society of island universes. Most island universes are sufficiently like one another to Permit of inferential understanding or even of mutual empathy or “feeling into. ” Thus, remembering our own bereavements and humiliations, we can condole with others in analogous circumstances, can put ourselves (always, of course, in a slightly Pickwickian sense) in their places. But in certain cases communication between universes is incomplete or even nonexistent.

The mind is its own place, and the Places inhabited by the insane and the exceptionally gifted are so different from the places where ordinary men and women live, that there is little or no common ground of memory to serve as a basis for understanding or fellow feeling. Words are uttered, but fail to enlighten. The things and events to which the symbols refer belong to mutually exclusive realms of experience. To see ourselves as others see us is a most salutary gift. Hardly less important is the capacity to see others as they see themselves.

But what if these others belong to a different species and inhabit a radically alien universe? For example, how can the sane get to know what it actually feels like to be mad? Or, short of being born again as a visionary, a medium, or a musical genius, how can we ever visit the worlds which, to Blake, to Swedenborg, to Johann Sebastian Bach, were home? And how can a man at the extreme limits of ectomorphy and cerebrotonia ever put himself in the place of one at the limits of endomorphy and viscerotonia, or, except within certain circumscribed areas, share the feelings of one who stands at the limits of mesomorphy and somatotonia?

To the unmitigated behaviorist such questions, I suppose, are meaningless. But for those who theoretically believe what in practice they know to be true–namely, that there is an inside to experience as well as an out- side–the problems posed are real problems, all the more grave for being, some completely insoluble, some soluble only in exceptional circumstances and by methods not available to everyone. Thus, it seems virtually certain that I shall never know what it feels like to be Sir John Falstaff or Joe Louis.

On the other hand, it had always seemed to me possible that, through hypnosis, for ex- ample, or autohypnosis, by means of systematic meditation, or else by taking the appropriate drug, I might so change my ordinary mode of consciousness as to be able to know, from the inside, what the visionary, the medium, even the mystic were talking about. From what I had read of the mescalin experience I was convinced in advance that the drug would admit me, at least for a few hours, into the kind of inner world described by Blake and AE.

But what I had expected did not happen. I had expected to lie with my eyes shut, looking at visions of many-colored geometries, of animated architectures, rich with gems and fabulously lovely, of landscapes with heroic figures, of symbolic dramas trembling perpetually on the verge of the ultimate revelation. But I had not reckoned, it was evident, with the idiosyncrasies of my mental make-up, the facts of my temperament, training and habits. I am and, for as long as I can remember, I have always been a poor visualizer.

Words, even the pregnant words of poets, do not evoke pictures in my mind. No hypnagogic visions greet me on the verge of sleep. When I recall something, the memory does not present itself to me as a vividly seen event or object. By an effort of the will, I can evoke a not very vivid image of what happened yesterday afternoon, of how the Lungarno used to look before the bridges were destroyed, of the Bayswater Road when the only buses were green and tiny and drawn by aged horses at three and a half miles an hour.

But such images have little substance and absolutely no autonomous life of their own. They stand to real, perceived objects in the same relation as Homer’s ghosts stood to the men of flesh and blood, who came to visit them in the shades. Only when I have a high temperature do my mental images come to independent life. To those in whom the faculty of visualization is strong my inner world must seem curiously drab, limited and uninteresting.

This was the world–a poor thing but my own–which I expected to see transformed into something completely unlike itself. The change which actually took place in that world was in no sense revolutionary. Half an hour after swallowing the drug I became aware of a slow dance of golden lights. A little later there were sumptuous red surfaces swelling and expanding from bright nodes of energy that vibrated with a continuously changing, patterned life.

At another time the closing of my eyes revealed a complex of gray structures, within which pale bluish spheres kept emerging into intense solidity and, having emerged, would slide noiselessly upwards, out of sight. But at no time were there faces or forms of men or animals. I saw no landscapes, no enormous spaces, no magical growth and metamorphosis of buildings, nothing remotely like a drama or a parable. The other world to which mescalin admitted me was not the world of visions; it existed out there, in what I could see with my eyes open.

The great change was in the realm of objective fact. What had happened to my subjective universe was relatively unimportant. I took my pill at eleven. An hour and a half later, I was sitting in my study, looking intently at a small glass vase. The vase contained only three flowers-a full-blown Belie of Portugal rose, shell pink with a hint at every petal’s base of a hotter, flamier hue; a large magenta and cream-colored carnation; and, pale purple at the end of its broken stalk, the bold heraldic blossom of an iris.

Fortuitous and provisional, the little nosegay broke all the rules of traditional good taste. At breakfast that morning I had been struck by the lively dissonance of its colors. But that was no longer the point. I was not looking now at an unusual flower arrangement. I was seeing what Adam had seen on the morning of his creation-the miracle, moment by moment, of naked existence.

In Vitro Fertilization (IVF), is the procedure whereby human babies are conceived, not in the womb but in a test tube or a Petri dish. This procedure has become one of the greatest developments in the world of medical technology. In Vitro Fertilization has given infertile couples the chance to conceive and bear a child from a full term of pregnancy. Without this procedure, their infertility would render them childless. There are many aspects of the IVF program that have been both praised and criticized.

The legal, ethical and social repercussions of the IVF program have created great debate and controversy. This essay will demonstrate the procedures used in the IVF program and set out the arguments for and against it. There are many reasons why couples cannot conceive or bear a child for a full term of pregnancy. The process of natural fertilization can only be achieved if the male and female reproductive organs are functioning without any abnormalities. The reproduction process begins with the male producing sperm in the testes and the female producing an egg in the ovaries.

Once every 28 days or so, an egg matures in the ovary, bursts from its follicle and enters the Fallopian tube. Once sexual intercourse has taken place, millions of sperm released from the penis swim up the vagina, through the uterus and into the Fallopian tube. A single sperm fertilizes the egg; the others are locked out. (Time, 1997, pg. 66) Once the egg has been fertilized, cell division begins and the embryo drifts down the Fallopian tube. The embryo reaches the uterus in about a week. The embryo anchors itself to the wall of the uterus where it develops into a foetus.

The foetus feeds off nutrients and oxygen provided by the placental lining in the uterus. There are several conditions in both males and females that cause abnormalities in the functioning of natural fertilization. Firstly, a condition in women called Endometriosis causes infertility. It is a condition where pieces of uterine tissue leak out of the uterus into the Fallopian tube. (Fertility Rights, 1993, pg. 6) It causes blockages in the Fallopian tubes and is associated with infertility even when the Fallopian tubes are not actually blocked. (Fertility Rights, 1993, pg6)

Secondly, the cause of infertility in men is a reduced sperm count, or low sperm motility, which greatly reduces the chances of successful fertilization. And lastly, about 10% of infertility is due to unknown causes. (Fertility Rights, 1993, pg. 6) After one year of infertility, couples whose infertility has been investigated without ascertaining cause may be admitted to IVF. The three causes of infertility mentioned are the most common among infertile couples, although, problems such as a loss of production of eggs due to radiation treatment or damage to the reproductive organs due to bad accidents can also be a reason for infertility.

If you think about it you would probably not notice it. Any type of bacteria is virtually invisible to the naked eye. We know that bacteria lives in every biotic and abiotic thing on this planet. Bacteria are in our every day life has adapted to or evolved just like humans. That is the key to all life on this planet being able to adapt or accommodate its surroundings. In the book Andromeda Strain the disease had come from outer space, that would be the most crucial and vital piece of information. To understand something you have to know what it is where it comes from and what compounds it is made up of.

The second thing that you have to recognize like in the case of the Andromeda Strain is if its compounds are earth like or if they are extraneous organisms from unknown reigns of space. You have to recognize what it is attracted to what it consumes and what if any waste it produces. This is very important to understanding how something works and survives. Although all of these steps would have to be taken in precautions steps in staying safe it would not be of use. The reason is because the Andromeda Strain had learned to adapt.

In considering the past this is very critical because the human population does not mind sharing its space things it can not see. There may have been many similar cases that have happened in our history that may have something to do with extraterrestrial life for example the common cold there is nothing common about it. Doctors are still confused about this nobody knows where or how long ago it came about. In retrospect, if Andromeda Strain had happened we probably would not have noticed. This would have been attributed to evaluation and the size of all bacteria.

We as a people accept what is told to us. The government would have made false claims to the Andromeda Strain to protect the human population from something that they did not need to know. These are things that will only make their lives more difficult and harder to understand. In theory if Andromeda Strain had happened life as we know it would go on just like it is now. That is why we are here now it is the ability to adapt to our environment. I think that in time the Andromeda Strain would have adapted enough that it would be beneficial to humans.

Homeostasis is the state of equilibrium in which the internal environment of the human body remains relatively constant. Two excellent examples of homeostasis are how the body maintains a constant temperature and blood pressure during strenuous physical activity or exercise. Although there are many other activities in the body that display homeostasis, I will only discuss these two. Temperature in the human body is usually kept at approximately 37 degrees Celsius. To maintain such a strict temperature, the body has a few functions to combat the outside elements.

People cannot make themselves cold as readily as make themselves hot, however I will mention both homeostasis functions. When the external temperature decreases, a portion of the brain called the hypothalamus detects the drop by means of the blood. To compensate, the brain sends chemical and electrical impulses to the muscles. These impulses tell the muscles to begin to contract and relax at very high intervals. This is commonly known as shivering. The production of Adenosine Triphosphate or ATP in the mitochondria of the muscles produces heat.

If the body temperature does not rise immediately after this, then a second function begins. The brain will signal the blood vessels near the skin to constrict or narrow in diameter. This occurs so the heat deep in the muscles is conserved. Since the vessels are now smaller in diameter, less blood is needed to fill them. Since less blood is needed through the vessels, the heart begins to slow. If the body remains in this slowed state, hypothermia could result. Hypothermia is the condition in which metabolic processes are inhibited.

The medical world has taken advantage f this by inducing hypothermia in patients that are undergoing organ transplants. To fight temperatures higher than normal, as in exercise or on hot days, the body reacts in the opposite way than with cold. Again, the hypothalamus detects the change of temperature in the blood. The brain signals blood vessels not to constrict, but to dilate. This increases the diameter of the vessels, and results in the need for more blood. Since more blood is needed to fill the vessels, the heart pumps faster and that causes respiration to increase.

The ncreased respiration will make the body exhale some of the internal heat, like placing a fan in a window to cool a room. The blood vessels are dilated so the heat deep in the muscles is easily released. Another commonly known mechanism to fight heat is sweating. Sweat glands found throughout the body are stimulated by the hypothalamus to excrete sweat and when the sweat evaporates, the skin is cooled. If the body is not cooled by the time all of the internal water supply is used, it could go into hypothermia. This is when the body becomes dehydrated and proteins begin to denature.

Hypothermia can result in certain death if the water supply is not immediately replenished. Some advantages to these mechanisms are the cleansing effect of sweating and weight loss. Sweat, when excreted, removes waste materials such as bacteria and water. Fat material, during exercise, is actually “eaten” by the body thus reducing overall weight. The second example of homeostasis is blood pressure regulation. When the hydrostatic pressure of blood is above normal, pressure sensors in the blood vessels tell the brain through chemical means. The brain will then stimulate he heart to contract or beat in slower intervals.

This will cause less blood to enter the blood vessels and that will lower the hydrostatic pressure. If the pressure is lower than normal, the exact opposite happens. The sensors in the vessels tell the brain and the brain will then make the heart beat faster so more blood enters the vessels and the pressure is raised. The body uses many mechanisms to regulate temperature and blood pressure. Be it stimuli to the heart from the brain or messages from the blood, the body maintains its internal environment through a process called homeostasis.

Throughout the process of the experiment, various concentrations of a solution of Sucrose and Water were placed into hydrolysis tubing and placed into and ambient environment of sterile water. An observation of a Starch solution in an ambient solution of sterile water and iodine was done to check for a chemical reaction of starch and iodine indicating diffusion. Also an observation of two segments of carrot placed each in Distilled and in Salt Water, to determine whether or not osmosis is taking place…

In an attempt to satisfy my hypophysis that when one placed a set amount of various molar concentrations of a solution of sucrose and distilled water into an ambient solution of distilled water, diffusion into the hydrolysis tubing with the solutions will occur, causing the tubes to gain weight. Also that a solution of starch and water in hydrolysis tubing placed in a Water/Iodine solution would generate a chemical reacion within the tube between the starch and the iodine, also indicating diffusion.

And lastly that two pieces of carrot, one placed in water, the other in salt water, would reveal that the salt water would draw moisture out of the carrot into the salty environment, causing the carrot in the salt water to become limp the opposite would occur in the other carrot. ” Throughout the process of the experiment, various concentrations of a solution of Sucrose and Water were placed into hydrolysis tubing which in turn are placed into and ambient environment of sterile water.

Also, an observation of a Starch solution in an ambient solution of sterile water and iodine was done to check for a chemical reaction between the starch and iodine indicating diffusion. Last, an observation of two segments of carrot placed one each in Distilled and in Salt Water, was done to determine whether or not osmosis is taking place between the carrots and the solution or the solution and the carrots.

Many plants orient their leaves in response to directional light signals. Heliotropic movements, or movements that are affected by the sun, are common among plants belonging to the families Malvaceae, Fabaceae, Nyctaginaceae, and Oxalidaceae. The leaves of many plants, including Crotalaria pallida, exhibit diaheliotropic movement. C. pallida is a woody shrub native to South Africa. Its trifoliate leaves are connected to the petiole by 3-4 mm long pulvinules (Schmalstig).

In diaheliotropic movement, the plants leaves are oriented perpendicular to the suns rays, thereby maximizing the interception of hotosynthetically active radiation (PAR). In some plants, but not all, his response occurs particularly during the morning and late afternoon, when the light is coming at more of an angle and the water stress is not as severe (Donahue and Vogelmann). Under these conditions the lamina of the leaf is within less than 15 from the normal to the sun. Many plants that exhibit diaheliotropic movements also show paraheliotropic response as well.

Paraheliotropism minimizes water loss by reducing the amount of light absorbed by the leaves; the leaves orient themselves parallel to the suns rays. Plants that exhibit paraheliotropic behavior usually do so at midday, when the suns rays are perpendicular to the ground. This reorientation takes place only in leaves of plants that are capable of nastic light-driven movements, such as the trifoliate leaf of Erythrina spp. (Herbert 1984). However, this phenomenon has been observed in other legume species that exhibit diaheliotropic leaf movement as well.

Their movement is temporarily transformed from diaheliotropic to paraheliotropic. In doing so, the interception of solar radiation is maximized uring the morning and late afternoon, and minimized during midday. The leaves of Crotalaria pallida also exhibit nyctinastic, or sleep, movements, in which the leaves fold down at night. The solar tracking may also provide a competitive advantage during early growth, since there is little shading, and also by intercepting more radiant heat in the early morning, thus raising leaf temperature nearer the optimum for photosynthesis.

Integral to understanding the heliotropic movements of a plant is determining how the leaf detects the angle at which the light is incident upon t, how this perception is transduced to the pulvinus, and finally, how this signal can effect a physiological response (Donahue and Vogelmann). In the species Crotalaria pallida, blue light seems to be the wavelength that stimulates these leaf movements (Scmalstig). It has been implicated in the photonastic unfolding of leaves and in the diaheliotropic response in Mactroptilium atropurpureum and Lupinus succulentus (Schwartz, Gilboa, and Koller 1987).

However, the light receptor involved can not be determined from the data. The site of light perception for Crotalaria pallida is the proximal ortion of the lamina. No leaflet movement occurs when the lamina is shaded and only the pulvinule is exposed to light. However, in many other plant species, including Phaseolus vulgaris and Glycine max, the site of light perception is the pulvinule, although these plants are not true suntracking plants. The compound lamina of Lupinus succulentus does not respond to a directional light signal if its pulvini are shaded, but it does respond if only the pulvini was exposed.

That the pulvinus is the site for light perception was the accepted theory for many years. However, experiments with L. alaestinus showed that the proximal 3-4 mm of the lamina needed to be exposed for a diaheliotropic response to occur. If the light is detected by photoreceptors in the laminae, somehow this light signal must be transmitted to the cells of the pulvinus. There are three possible ways this may be done. One is that the light is channeled to the pulvinus from the lamina.

However, this is unlikely since an experiment with oblique light on the lamina and vertical light on the pulvinus resulted in the lamina responding to the oblique light. Otherwise, the light coming from the amina would be drowned out by the light shining on the pulvinus. Another possibility is that some electrical signal is transmitted from the lamina to the pulvinus as in Mimosa. It is also possible that some chemical is transported from the lamina to the pulvinus via the phloem. These chemicals can be defined as naturally occuring molecules that affect some physiological process of the plant.

They may be active in concentrations as low as 10-5 to 10-7 M solution. Whatchemical, if any, is used by C. pallida to transmit the light signal from the lamina of the leaflet to its pulvinule is unknown. Periodic leaf movement factor 1 (PLMF 1) has been isolated from Acacia karroo, a plant with pinnate leaves that exhibits nychinastic sleep movements, as well as other species of Acacia, Oxalis, and Samanea. PLNF 1 has also been isolated from Mimosa pudica, as has the molecule M-LMF 5 (Schildknecht).

The movement of the leaflets is effected by the swelling and shrinking of cells on opposite sides of the pulvinus (Kim, et al. ) In nyctinastic plants, cells that take up water when a leaf rises and lose water when the leaf lowers are called extensor cells. The opposite occurs in the flexor cells (Satter and Galston). When the extensor cells on one side of the pulvinus take up water and swell, the flexor cells on the other side release water and shrink. The opposite of this movement can also occur. However, the terms extensor and flexor are not rigidly defined.

Rather, the regions are defined according to function, not position. Basically, the pulvini cells that are on the adaxial (facing the light) side of the pulvinus are the flexor cells, and the cells on the abaxial side are the extensor cells. Therefore, the terms can mean different cells in the same pulvinus at varying times of the day. By oordinating these swellings and shrinkings, the leaves are able to orient themselves perpendicular to the sunlight in diaheliotropic plants. Leaf movements are the result of changes in turgor pressure in the pulvinus.

The pulvinus is a small group of cells at the base of the lamina of each leaflet. The reversible axial expansion and contraction of the extensor and flexor cells take place by reversible changes in the volume of their motor cells. These result from massive fluxes of osmotically active solutes across the cell membrane. K+ is the ion that is usually implicated in this process, nd is balanced by the co-transport of Cl- and other organic and inorganic anions. While the mechanisms of diaheliotropic leaf movements have not been studied extensively, much data exists detailing nyctinastic movements.

Several ions are believed to be involved in leaf movment. These include K+, H+, Cl-, malate, and other small organic anions. K+ is the most abundant ion in pulvini cells. Evidence suggests that electrogenic ion secretion is responsible for K+ uptake in nyctinastic plants. The transition from light to darkness activates the H+/ATPase in the flexor cells of the pulvinus. This leads to the release of bound K+ from the apoplast and movement of the K+ into the cells by way of an ion channel.

This increase in K+ in the cell decreases the osmotic potential of the cells, and water than influxes into the flexor cells, increasing their volume. In Samanea, K+ levels changed four-fold in flexor cells during the transition from light to darkness. In a similar experiment, during hour four of a photoperiod, the extensor apoplast of Samanea had 14mM and the flexor apoplast had 23 mM of K+. After the lights were turned off, inducing nyctinastic ovements, the K+ level in the apoplast rose to 72 mM in the extensor cells and declined to 10mM in the flexor cells.

Therefore, it appears that swelling cells take up K+ from the apoplast and shrinking cells release K+ into the apoplast. In the pulvinus of Samanea saman, depolarization of the plasma membrane opens K+ channels (Kim et al). The driving force for the transport of K+ across the cell membranes is apparently derived from activity of an electrogenic proton pump. This creates an electrochemical gradient that allows for K+ movement. From concentration measurements in pulvini, K+ seems to be the most important on involved in the volume changes of these cells.

How then, is K+ allowed to be at higher concentrations inside a cell than out of it? Studies indicate that the K+ channels are not always open. In protoplasts of Samanea saman, K+ channels were closed when the membrane potential was below -40mV and open when the membrane potential was depolarized to above -40mV. A voltage-gated K+ channel that is opened upon depolarization has been observed in every patch clamp study of the plasma membranes of higher plants, including Samanea motor cells and Mimosa pulviner cells.

A long long time ago, in a galaxy not too far away, was a little blue planet called Earth, and on this world not a single mammal lived. However a lot of time has past since then and we now have lots of furry creatures that are collectively called mammals. How did they get their? Where did they come from? These are the kinds of questions that led me to my subject of choice. I will endeavor to provide examples, using specific transitional fossils, to show that mammals have evolved from a group of reptiles and were simply not placed here by unknown forces.

Before I begin, I would like to define some terms so that nobody gets left in the dust. The term transitional fossil can be used in conjunction with the term general lineage, together they help explain the how one species became another. “General lineage”: This is a sequence of similar genera or families, linking an older to a very different younger group. Each step in the sequence consists of some fossils that represent certain genus or family, and the whole sequence often covers a span of tens of millions of years.

A lineage like this shows obvious intermediates for every major structural change, and the fossils occur roughly (but often not exactly) in the expected order. However, usually there are still gaps between ach of the groups. Sometimes the individual specimens are not thought to be directly ancestral to the next-youngest fossils (e. g. they may be “cousins”” or “uncles” rather than “parents”). However they are assumed to be closely related to the actual ancestor, since the have similar intermediate characteristics.

Where Does It All Begin ? Mammals were derived during the Triassic Period ((from 245 to 208 million years ago) It began with relatively warm and wet conditions, but as it progressed conditions became increasingly hot and dry. ) from members of the reptilian order Therapsida. The therapsids, members of the subclass Synapsida sometimes called the mammal-like reptiles),generally were unimpressive in relation to other reptiles of their time. Synapsids were present in the Carboniferous Period (about 280 to 345 million years ago) and are one of the earliest known reptilian groups.

Although therapsids were primarily predators by nature, some adaptations included a herbivorous species as well, they were generally small active carnivores. Primitive therapsids are present as fossils in certain Middle Permian deposits; later forms are known from every continent except Australia but are most common in the Late Permian and Early Triassic of South Africa. The several features that separate modern reptiles from modern mammals doubtlessly evolved at different rates.

Many attributes of mammals are correlated with their highly active lifestyle; for example, efficient double circulation of blood with a completely four-chambered heart, anucleate and biconcave erythrocytes (blood cells), the diaphragm, and the secondary palate (which separates passages of food and air and allows breathing during mastication (chewing) or suckling). Hair for insulation correlates with endothermy (being warm-blooded), the physiological maintenance of individual emperature independent of the environmental temperature, and endothermy allows high levels of sustained activity.

The unique characteristics of mammals thus would seem to have evolved as a complex interrelated system. Transitions to New Higher Taxa Transitions often result in a new “higher taxon” (a new genus, family, order, etc. ) from a species belonging to different, older taxon. There is nothing magical about this. The first members of the new group are not bizzare, they are simply a new, slightly different species, barely different from the parent species. Eventually they give rise to a more different species, which in urn gives rise to a still more different species, and so on, until the descendents are radically different from the original parent.

For example, the Order Perissodactyla (horses) and the Order Cetacea (whales) can both be traced back to early Eocene animals that looked only marginally different from each other, and didn’t look at all like horses or whales. (They looked more like small, dumb foxes with raccoon-like feet and simple teeth. ) But over the following tens of millions of years, the descendents of those animals became more and more different, and now we call them two different orders.

Major Skeletal Differences (derived from the fossil record) The mammalian skeletal system shows a number of advances over that of reptiles. he mode of ossification (process of bone formation) of the long bones is one characteristic. In reptiles each long bone has a single centre of ossification, and replacement of cartilage by bone proceeds from the centre toward the ends. In mammals secondary centres of ossification develop at the ends of the bones. Mammalian skeletal growth is termed determinate, for once the actively growing zone of cartilage is used up, growth in length ceases. As in ll bony vertebrates, of course, there is continual renewal of bone throughout life.

The advantage of secondary centres of ossification at the ends of bones lies in the fact that the bones have strong articular surfaces before the skeleton is mature. In general, the skeleton of the adult mammal has less structural cartilage than does that of a reptile. The skeletal system of mammals and other vertebrates is broadly divisible into axial and appendicular portions. The axial skeleton consists of the skull, the backbone and ribs, and serves primarily to protect the central nervous system. he limbs and their girdles make up the appendicular skeleton.

In addition, there are skeletal elements derived from gill arches of primitive vertebrates, collectively called the visceral skeleton. Visceral elements in the mammalian skeleton include jaws, the hyoid apparatus supporting the tongue, and the auditory ossicles of the middle ear. The postcranial axial skeleton in mammals general has remained the rather conservative during the course of evolution. The vast majority of mammals have seven cervical (neck) vertebrae, and do not have lumbar ribs, both characteristics are unlike reptiles.

The skull of mammals differs markedly from that of reptiles because of the great expansion of the brain. The sphenoid bones that form the reptilian braincase form only the floor of the braincase in mammals. In mammals a secondary palate, that is not present in reptiles, is formed by processes of the maxillary bones and the palatines. The secondary palate separates the nasal passages from the oral cavity and allows continuous breathing while chewing or suckling. The bones of the mammalian middle ear are a diagnostic of the class.

The three auditory ossicles form a series of levers that serve mechanically to ncrease the amplitude of sound waves reaching the tympanic membrane, or eardrum, produced as disturbances of the air. The innermost bone is the stapes, or “stirrup bone. ” It rests against the oval window of the inner ear. The stapes is homologous with the entire stapedial structure of reptiles, which in turn was derived from the hyomandibular arch of primitive vertebrates. The incus, or “anvil”, articulates with the stapes.

The incus was derived from the quadrate bone, which is involved in the jaw articulation in reptiles. The malleus, or “hammer”, rests against the tympanic membrane and articulates with the incus. The malleus is the homologue of the reptilian articular bone. The mechanical efficiency of the middle ear has thus been increased by the incorporation of two bones of the reptilian jaw assemblage. In mammals the lower jaw is a single bone, the dentary. The mammalian limbs and girdles have been greatly modified with locomotor adaptations.

The primitive mammal had well developed limbs and was five-toed. In each limb there two distal bones (radius and ulna in the forelimb; tibia and fibula in the hindlimb) and a single proximal bone (humerus; femur). The number of phalangeal bones in each digit, numbered from inside outward, is -3-3-3-3 in primitive mammals and 2-3-4-5-4 in primitive reptiles. Modifications in mammalian limbs have involved reduction, loss, or fusion of bones. Loss of the clavicle from the shoulder girdle, reduction in the number of toes. The Transition This is a documented transition between vertabrate classes.

Slight hint of different tooth types. Still has some extremely primitive amphibian features. – Varnops (early Permian) – Temporal fenestra further enlarged. Braincase floor shows first mammalian tendencies and first signs of stronger attachment to the rest of the skull. Lower jaw shows first changes in jaw structure. Body narrower, deeper, vertebral column more strongly constructed. Ilium further enlarged, lower-limb musculature starts to change. This animal was more mobile and active. Too late to be a true ancestor, must be a “cousin”.

Haptodus (late Pennsylvanian) – One of the first known sphenacodonts, showing the initiation of sphenacodont features while retaining many primitive features of the ophiacodonts. Skull more strongly attached to the braincase. Teeth become size differentiated, with the in the canine region and fewer teeth overall. Stronger jaw muscles. Vertebrae parts and joints more mammalian. Neural spines on vertebrae longer. Hip strengthened by fusing to three sacral vertebrae instead of just two. Limbs very well developed. – Dimetrodon, Sphenacodon (early Permian) – More advanced pelycosaurs, clearly losely related to the first therapsids.

Dimetrodon is almost definitely a “cousin” and not a direct ancestor, but as it is known from very complete fossils, it’s a good model for sphenacodont anatomy. Medium sized fenestra. Teeth further differentiated, with small incisors, two huge deep-rooted upper canines on each side, followed by smaller cheek teeth, all replaced continuously. Fully reptilian jaw hinge. Lower jaw made of multiple bones and first signs of a bony prong later involved in the eardrum, but there was eardrum yet, so these reptiles could only hear ground-borne vibrations (they did have a reptilian iddle ear).

Vertebrae had still longer neural spines (especially so in Dimetrodon, which had a sail), and longer transverse spines for stronger locomotion muscles. – Procynosuchus (late Permian) – The first known cynodont – A famous group of very mammal-like therapsid reptiles, sometimes considered to be the first mammals. Probably arose from the therocephalians, judging from the distinctive secondary palate and numerous other skull characters. Enormous temporal fossae for very strong jaw muscles, formed by just one of the reptilian jaw muscles, which has now become the mammalian masseter (muscle).

Secondary palate now omposed mainly of palatine bones, rather than vomers and maxilla as in older forms. Lower incisor teeth were reduced to four per side, instead of the previous six. Dentary now is 3/4 of lower jaw; the other bones are now a small complex near the jaw hinge. Vertebral column starts to look mammalian: first two vertebrae modified for head movements, and lumbar vertebrae start to lose ribs. A diaphragm may have been present. -Thrinaxodon (early Triassic) – A more advanced cynodont. Further development of several of the cynodont features seen already.

Temporal fenestra still larger, larger jaw muscle attachments. Bony econdary palate almost complete. Functional division of teeth: incisors (four uppers and three lowers), canines, and then 7-9 cheek teeth with cusps for chewing. The cheek teeth were all alike (no premolars and molars). The whole locomotion was more agile. Number of toe bones is 2-3-4-4-3, intermediate between the reptile number (2-3-4-5-4) and the mammalian (2-3-3-3-3), and the “extra” toe bones were tiny. – Exaeretodon (late Triassic) – True bony secondary palate formed exactly as in mammals.

Mammalian toe bones (2-3-3-3-3). Lumbar ribs totally lost. – Sinoconodon (early Jurassic) – Proto-mammal. Eyesocket fully mammalian now closed medial wall). Hindbrain expanded. Permanent cheek teeth, like mammals, but the other teeth were still replaced several times. Mammalian jaw joint stronger, with large dentary condyle fitting into a distinct fossa on the squamosal. This final refinement of joint automatically makes this animal a true “mammal”. – Peramus (late Jurassic) – An advanced placental-type mammal.

The closest known relative of the placentals and marsupials. Has attained a fully mammalian three- boned middle ear with excellent high-frequency hearing. – Steropodon galmani (early Cretaceous) – The first known monotreme (egg laying ammals). – Pariadens kirklandi (late Cretaceous) – The first definite marsupial. – Kennalestes and Asioryctes (late Cretaceous) – Small, slender animals; eyesockets open behind; simple ring to support eardrum; primitive placental-type brain with large olfactory bulbs; basic primitive mammalian tooth pattern. Canine now double rooted.

Still just a trace of a non-dentary bone (the coronoid process), on the otherwise all-dentary jaw. “Could have given rise to nearly all subsequent placentals. ” says Carroll (1988) So, by the late Cretaceous the three groups of modern mammals were in lace: monotremes, marsupials, and placentals. Placentals appear to have arisen in East Asia and spread to the Americas by the end of the Cretaceous. In the late Cretaceous, placentals and marsupials had started to diversify a bit, and after the dinosaurs died out, in the Paleocene, this diversification accelerated.

For instance, in the mid-Paleocene the placental fossils include a very primitive primate-like animal (Purgatorius – known only from a tooth, though, and may actually be an early ungulate), a herbivore-like jaw with molars that have flatter tops for better grinding, and also an insectivore (Paranygenulus).

Because the characteristics that separate reptiles and mammals evolved at different rates and in a response to a variety of interrelated conditions, at any point in the period of transition from reptiles to mammals there were forms that combined various characteristics of both groups. uch a pattern of evolution is termed “mosaic” and is a common phenomenon in those transitions marking the origin of major new adaptive types. To simplify definitions and to allow the strict delimitation of the Mammalia, some authors have suggested basing the boundary on a single character, the articulation of the jaw between he dentary and squamosal bones and the attendent movement of accessory jaw bones to the middle ear as auditory ossicles.

The use of a single character allows the placement in a logical classification of numerous fossil species, other mammalian. characters of which, such as the degree of endothermy and nursing of young and the condition of the internal organs, probably never will be evaluated. It must be recognized, however, that if the advanced therapsids were alive today, taxonomists would be hard-put to decide which to place in the Reptilia and which in the Mammalia.

A man is involved in a severe car crash in Florida which has left him brain-dead with no hope for any kind of recovery. The majority of his vital organs are still functional and the man has designated that his organs be donated to a needy person upon his untimely death. Meanwhile, upon checking with the donor registry board, it is discovered that the best match for receiving the heart of the Florida man is a male in Oregon who is in desperate need of a heart transplant. Without the transplant, the man will most certainly die within 48 hours. The second man’s tissues match up perfectly with the brain-dead man’s in Florida.

This seems like an excellent opportunity for a heart transplant. However, a transplant is currently not a viable option for the Oregon man since he is separated by such a vast geographic distance from the organ. Scientists and doctors are currently only able to keep a donor heart viable for four hours before the tissues become irreversibly damaged. Because of this preservation restriction, the donor heart is ultimately given to someone whose tissues do not match up as well, so there is a greatly increased chance for rejection of the organ by the recipient.

As far as the man in Oregon goes, he will probably not receive a donor heart before his own expires. Currently, when a heart is being prepared for transplantation, it is simply submerged in an isotonic saline ice bath in an attempt to stop all metabolic activity of that heart. This cold submersion technique is adequate for only four hours. However, if the heart is perfused with the proper media, it can remain viable for up to 24 hours. The technique of perfusion is based on intrinsically simple principles. What occurs is a physician carefully excises the heart from the donor.

He then accurately trims the vessels of the heart so they can be easily attached to the perfusion apparatus. After trimming, a cannula is inserted into the superior vena cava. Through this cannula, the preservation media can be pumped in. What if this scenario were different? What if doctors were able to preserve the donor heart and keep it viable outside the body for up to 24 hours instead of only four hours? If this were possible, the heart in Florida could have been transported across the country to Oregon where the perfect recipient waited.

The biochemical composition of the preservation media for hearts during the transplant delay is drastically important for prolonging the viability of the organ. If a media can be developed that could preserve the heart for longer periods of time, many lives could be saved as a result. Another benefit of this increase in time is that it would allow doctors the time to better prepare themselves for the lengthy operation. The accidents that render people brain-dead often occur at night or in the early morning. Presently, as soon as a donor organ becomes available, doctors must immediately go to work at transplanting it.

This extremely intricate and intense operation takes a long time to complete. If the transplanting doctor is exhausted from working a long day, the increase in duration would allow him enough time to get some much needed rest so he can perform the operation under the best possible circumstances. Experiments have been conducted that studied the effects of preserving excised hearts by adding several compounds to the media in which the organ is being stored. The most successful of these compounds are pyruvate and a pyruvate containing compound known as perfluoroperhydrophenanthrene-egg yolk phospholipid (APE-LM).

It was determined that adding pyruvate to the media improved postpreservation cardiac function while adding glucose had little or no effect. To test the function of these two intermediates, rabbit hearts were excised and preserved for an average of 24. 5 1 0. 2 hours on a preservation apparatus before they were transplanted back into a recipient rabbit. While attached to the preservation apparatus, samples of the media output of the heart were taken every 2 hours and were assayed for their content.

If the compound in the media showed up in large amounts in the assay, it could be concluded that the compound was not metabolized by the heart. If little or none of the compound placed in the media appeared in the assay, it could be concluded that compound was used up by the heart metabolism. The hearts that were given pyruvate in their media completely consumed the available substrate and were able to function at a nearly normal capacity once they were transplanted. Correspondingly, hearts that were preserved in a media that lacked pyruvate had a significantly lower rate of contractile function once they were transplanted.

The superior preservation of the hearts with pyruvate most likely resulted from the hearts use of pyruvate through the citric acid cycle for the production of energy through direct ATP synthesis (from the reaction of succinyl-CoA to succinate via the enzyme succinyl CoA synthetase) as well as through the production of NADH + H+ for use in the electron transport chain to produce energy. After providing a preservation media that contained pyruvate, a better recovery of the heart tissue occurred. Most of the pyruvate consumed during preservation was probably oxidized by the myocardium in the citric acid cycle.

Only a small amount of excess lactate was detected by the assays of the preservation media discharged by the heart. The lactate represented only 15% of the pyruvate consumed. If the major metabolic route taken by pyruvate during preservation had been to form lactate dehydrogenase for regeneration of NAD+ for continued anaerobic glycolysis, rather than by the aerobic citric acid cycle (pyruvate oxidation), then a higher ratio of excess lactate produced to pyruvate consumed would have been observed. Hearts given a glucose substrate did not transport or consume that substrate, even when it was provided as the sole exogenous substrate.

It might be expected that glucose would be used up in a manner similar to that of pyruvate. This expectation is because glucose is a precursor to pyruvate via the glycolytic pathway however, this was not the case. It was theorized this lack of glucose use may have been due to the fact that the hormone insulin was not present in the media. Without insulin, one may think the tissues of the heart would be unable to adequately take glucose into their tissues in any measurable amount, but this is not the case either.

It is known that hearts working under physiologic conditions do use glucose in the absence of insulin, but glucose consumption in that situation is directly related to the performance of work by the heart, not the presence of insulin. To further test the effects of the addition of insulin to the glucose media, experiments were done in which the hormone was included in the heart preservation media5-7. Data from those studies does not provide evidence that the hormone is essential to insure glucose use or to maintain the metabolic status of the heart or to improve cardiac recovery.

In a hypothermic (80C) setting, insulin did not exert a noticeable benefit to metabolism beyond that provided by oxygen and glucose. This hypothermic setting is analogous to the setting an actual heart would be in during transportation before transplant. Another study was done to determine whether the compound perfluoroperhydrophenanthrene-egg yolk phospholipid, (APE-LM) was an effective media for long-term hypothermic heart preservation3. Two main factors make APE-LM an effective preservation media. ) It contains a lipid emulsifier which enables it to solubilize lipids. From this breakdown of lipids, ATP can be produced. (2)

APE-LM contains large amounts of pyruvate. As discussed earlier, an abundance of energy is produced via the oxidation of pyruvate through the citric acid cycle. APE-LM-preserved hearts consumed a significantly higher amount of oxygen than hearts preserved with other media. The higher oxygen and pyruvate consumption in these hearts indicated that the hearts had a greater metabolic oxidative activity during preservation than the other hearts.

The higher oxidative activity may have been reflective of greater tissue perfusion, especially in the coronary beds, and thereby perfusion of oxygen to a greater percentage of myocardial cells. Another factor contributing to the effectiveness of APE-LM as a transplantation media is its biologically compatible lipid emulsifier, which consists primarily of phospholipids and cholesterol. The lipid provides a favorable environment for myocardial membranes and may prevent perfusion-related depletion of lipids from cardiac membranes.

The cholesterol contains a bulky steroid nucleus with a hydroxyl group at one end and a flexible hydrocarbon tail at the other end. The hydrocarbon tail of the cholesterol is located in the non polar core of the membrane bilayer. The hydroxyl group of cholesterol hydrogen-bonds to a carbonyl oxygen atom of a phospholipid head group. Through this structure, cholesterol prevents the crystallization of fatty acyl chains by fitting between them. Thus, cholesterol moderates the fluidity of membranes.

The reason there are currently such strict limits on the amount of time a heart can remain viable out of the body is because there must be a source of energy for the heart tissue if it is to stay alive. Once the supply of energy runs out, the tissue suffers irreversible damage and dies. Therefore, this tissue cannot be used for transplantation. If hypothermic hearts are not given exogenous substrates that they can transport and consume, like pyruvate, then they must rely on glycogen or lipid stores for energy metabolism.

The length of time that the heart can be preserved in vitro is thus related to the length of time before these stores become too low to maintain the required energy production needs of the organ. It is also possible that the tissue stores of ATP and phosphocreatine are critical factors. It is known that the amount of ATP in heart muscle tissues is sufficient to sustain contractile activity of the muscle for less than one second. This is why phosphocreatine is so important. Vertebrate muscle tissue contains a reservoir of high-potential phosphoryl groups in the form of phosphocreatine.

Phosphocreatine can transfer its phosphoryl group to ATP according to the following reversible reaction:phosphocreatine + ADP + H+ 9 ATP + creatinePhosphocreatine is able to maintain a high concentration of ATP during periods of muscular contraction. Therefore, if no other energy producing processes are available for the excised heart, it will only remain viable until its phosphocreatine stores run out. A major obstacle that must be overcome in order for heart transplants to be successful, is the typically prolonged delay involved in getting the organ from donor to recipient.

The biochemical composition of the preservation media for hearts during the transplant and transportation delays are extremely important for prolonging the viability of the organ. It has been discovered that adding pyruvate, or pyruvate containing compounds like APE-LM, to a preservation medium greatly improves post-preservation cardiac function of the heart. As was discussed, the pyruvate is able to enter the citric acid cycle and produce sufficient amounts of energy to sustain the heart after it has been excised until it is transplanted.

Increasing the amount of time a heart can remain alive outside of the body prior to transplantation from the current four hours to 24 hours has many desirable benefits. As discussed earlier, this increase in time would allow doctors the ability to better match the tissues of the donor with those of the recipient. Organ rejection by recipients occurs frequently because their tissues do not suitably match those of the donors. The increase in viability time would also allow plenty of opportunity for the organ to be transported to the needy person, even if it must go across the country.

The cell is the fundamental structural unit of all living organisms. Some cells are complete organisms, such as the unicellular bacteria and protozoa; others, such as nerve, liver, and muscle cells, are specialized components of multi-cellular organisms. Cells range in size from the smallest bacteria-like mycoplasmas, which are 0. 1 micrometer in diameter, to the egg yolks of ostriches, which are about 8 cm (about 3 in) in diameter.

Although they may differ widely in appearance and function, all cells have a surrounding membrane and an internal, water-rich substance called the cytoplasm, the composition of which differs significantly from the external environment of the cell. Within the cell is genetic material, deoxyribonucleic acid (DNA), containing coded instructions for the behavior and reproduction of the cell and also the chemical machinery for the translation of these instructions into the manufacture of proteins.

Viruses are not considered cells because they lack this translation machinery; they must parasitize cells in order to translate their own genetic code and reproduce themselves. Cells are of two distinctly different types, prokaryotes and eukaryotes; thus, the living world is divided into two broad categories. The DNA of prokaryotes is a single molecule in direct contact with the cell cytoplasm, whereas the DNA of eukaryotes is much greater in amount and diversity and is contained within a nucleus separated from the cell cytoplasm by a membranous nuclear envelope.

Many eukaryotic cells are further divided into compartments by internal membranes in addition to the nuclear envelope, whereas prokaryotic cells never contain completely internal membranes. The prokaryotes include the mycoplasmas, bacteria, and blue-green algae. The eukaryotes comprise all plant and animal cells. In general, plant cells differ from animal cells in that they have a rigid cell wall exterior to the plasma membrane; a large vacuole, or fluid-filled pouch; and chloroplasts that convert light energy to chemical energy for the synthesis of glucose.

Structure and Function Cells are composed primarily of oxygen, hydrogen, carbon, and nitrogen, the elements that make up the majority of organic compounds. The most important organic compounds in a cell are proteins, nucleic acids, lipids, and polysaccharides (carbohydrates). The \”solid\” structures of the cell are complex combinations of these large molecules. Water makes up 60 to 65 percent of the cell, because water is a favorable environment for biochemical reactions.

All cells are dynamic at some stage of their life cycle, in the sense that they use energy to perform a variety of cell functions: movement, growth, maintenance and repair of cell structure, reproduction of the cell, and manufacture of specialized cell products such as enzymes and hormones. These functions are also the result of interactions of organic molecules. Plasma Membrane The plasma membrane, a continuous double layer of phospholipid molecules 75 to 100 angstroms thick, constitutes the boundary between the cell and its external environment.

In addition to lipids, the plasma membrane has protein components (polypeptides) that are associated with either the outer or inner surfaces of its layers or are buried within them. The structure as a whole is selectively permeable, or semipermeable; that is, it permits the exchange of water and selected atoms and molecules between the cell exterior and interior. This is vital to the cell because while the plasma membrane helps maintain high local concentrations of organic molecules within the cell, it also allows interaction between the cell and its external environment.

The plasma membrane mediates such interactions in various ways. The exchange of mineral ions and small nutrient molecules is controlled by plasma membrane proteins that act as pumps, carriers, and channels. The plasma membrane also participates in the exchange of larger molecules through phagocytosis, the engulfing of large food particles; endocytosis, the intake of fluids and membrane components; and exocytosis, the expulsion of cell products or cell waste. In addition, the plasma membrane contains receptors that selectively receive nerve and hormone signals and transmit them to the interior of the cell.

Finally, direct cell-to-cell interactions can occur through specialized regions of the plasma membrane known as junctions. Organs such as the skin and the small intestine consist of cells held together by tight junctions and local thickenings, or desmosomes, which constitute another type of junction. Cells can communicate electrically through a third type of junction, called a gap junction, that consists of tiny protein \”tunnels\” between two cells, through which tiny \”message\” molecules and ions may be passed.

When the plasma membranes of two cells are continuous, an actual bridge of cytoplasm forms between them; in plants these bridges are called plasmodesmata. Cell Walls Exterior to the plasma membrane of most plant cells and bacteria is a cell wall, a cell product made largely of complex polysaccharides. In higher plants the polysaccharide is cellulose. The presence of a cell wall makes these cells rigid and sturdy, but it poses special problems for the transport of substances into and out of the cell.

Cytoplasm The cytoplasm is the water-rich matrix within a cell that contains and surrounds the other cellular contents. It is more like a viscous gel than a watery solution, but it liquefies when shaken or stirred. Such gel-to-sol transitions are thought by some cell biologists to play a role in the movement of a cell’s components from place to place within the cell. Rapid movement of cell components is called either streaming or cyclosis, depending on whether it occurs linearly or circularly.

Through an electron microscope the cytoplasmic gel appears as a three-dimensional lattice of slender, protein-rich strands in a continuous water-rich phase. Because the latticework is reminiscent of the internal structure of spongy bone, which is composed of many struts, or trabeculae, it is called the microtrabecular lattice (MTL). The MTL appears to interconnect and support the other \”solid\” structures of the cell. The composition and function of the MTL are as yet still unknown, but it is thought to control the spatial arrangement of cell components within the cytoplasm.

Cytoskeleton The so-called cytoskeleton influences the shape of the cell in much the same way tent poles determine the shape of a tent. Without the cytoskeleton a cell tends to become spherical. The cytoskeleton probably gives direction to the movement of components within the cytoplasm as well and participates in movement of the cell itself. The cytoskeleton is composed of three main filament types: the microtubules, microfilaments, and intermediate-sized filaments that are supported and distributed within the MTL. Microtubules are long rigid cylinders that act as the bones of the cell.

They also may act as tracks along which intracellular components are transported. The walls of the cylinders are composed of two proteins, alpha- and beta-tubulin. Microfilaments are composed of actin, a major protein of muscle. They often occur in long bundles called stress fibers and may act as the muscles of the cell. The intermediate-sized filaments are a heterogeneous class of proteins whose function is largely unknown. Nucleus The membrane-bounded structures contained within the cytoplasm of eukaryotes are referred to as organelles.

The nucleus is the most easily recognizable of these. DNA, combined with protein, is organized inside the nucleus into structural units called chromosomes, which usually occur in identical pairs. The DNA in each chromosome is a single, very long, highly coiled molecule subdivided into functional subunits called genes. Genes contain the coded instructions for the assembly of polypeptides and larger proteins. Together the chromosomes contain all the information needed to build an identical functioning copy of the cell.

The nucleus is surrounded by an envelope of two concentric membranes. Interaction between the nuclear contents and the surrounding cytoplasm is permitted through holes, called nuclear pores, in this envelope. The nucleus also contains a specialized region, the nucleolus, where nucleoprotein particles are assembled. These particles migrate through the nuclear pores into the cytoplasm, where they are modified to become ribosomes. Ribosomes Ribosomes are the \”factories\” where the instructions encoded in the DNA of the nucleus are translated to make proteins.

The instructions are carried from the DNA to the ribosomes by long nucleic-acid molecules called messenger ribonucleic acids (RNAs). Endoplasmic Reticulum (Er) Among the other membranous structures within the eukaryotic cell are extensive membrane systems that make up the smooth and the rough endoplasmic reticulum. The smooth endoplasmic reticulum often takes the form of branching tubes The rough endoplasmic reticulum is made up of sheet-like flattened sacs, which often are stacked one on top of the other; the term rough refers to the numerous ribosomes that dot the cytoplasmic surfaces of the sacs.

The rough endoplasmic reticulum is one of the sites of protein synthesis in the cytoplasm. Proteins are synthesized on the cytoplasmic surface and pass through the membrane to become sequestered within the sacs. These packaged proteins are destined for secretion to the outside of the cell. Other proteins, synthesized on ribosomes that are not attached to membranes, are not secreted and remain as structural proteins or metabolic enzymes. Golgi Apparatus Similar in appearance to and perhaps continuous with the ER is a region of smooth, stacked membranous sacs known as the Golgi apparatus.

Cell biologists think that the apparatus modifies proteins, after they are synthesized and packaged on the rough endoplasmic reticulum, by linking them with sugars or other molecules. Lysosomes Lysosomes are membrane-bounded bags, or vesicles, containing digestive enzymes. Their normal function is digestion of complex nutrients and broken-down organelles. In disease fighting, the lysosomes of white blood cells aid in the digestion of engulfed bacteria and other foreign or toxic materials. Mitochondria and Chloroplasts (Plastids)

Mitochondria are the powerhouses of the animal cell, where the products of the enzymatic breakdown, or metabolism, of nutrients such as glucose are converted into energy in the form of the molecule adenosine triphosphate (ATP). This process uses up oxygen and is called aerobic respiration. Plants possess, in addition to mitochondria, similar organelles called chloroplasts. Each chloroplast contains the green pigment chlorophyll, which is used to convert light energy from the sun into ATP. This process is called photosynthesis.

Cilia and Flagella Some cells have flexible, whip-like external appendages called cilia and flagella, which are used for locomotion and for capturing food. Cilia are 3 to 10 micrometers long and are found on protozoa as well as in human oviducts and respiratory tracts. In the respiratory tract they sweep large particles up the trachea and prevent them from passing into the lungs. Flagella, which may be ten times as long, are found on some protozoa and unicellular plants, and they are used for locomotion by the sperm of higher organisms.

Eukaryotic cilia and flagella are composed of microtubules covered by a membrane sheath. Prokaryotic flagella are more slender and are composed of the protein flagellin. They propel the cell by rotating like the propeller of a ship rather than by a whipping motion. Centrioles and Basal Bodies All animal and some plant cells contain a pair of centrioles, which are cylindrical structures composed of short microtubules. They are surrounded by a cloud of fuzzy material, the exact function of which is unknown. Centrioles control the arrangement of microtubules in the cell cytoskeleton.

Basal bodies, which are similar, are structures that anchor cilia and flagella within the cytoplasm, just inside the plasma membrane. Centrioles and basal bodies both contain DNA and apparently can duplicate themselves independently of duplication of the entire cell. Division, Reproduction, and Differentiation All cells are the products of the division of preexisting cells. Simple cell division, or asexual reproduction, normally results in the production of two identical daughter cells, each containing a set of chromosomes identical with those of the parent cell.

Before the onset of division, a cell grows to roughly twice its original size. In doing so it duplicates its DNA, so that each chromosome is doubled. During division the duplicate sets are physically separated, following longitudinal splitting of each double chromosome, and are transported into opposite sides of the cell. The cell then constricts around its equator and pinches in two. In cells that contain chromosomes, the separation of chromosomes during division requires an oblong scaffold of parallel microtubules, along which the chromosomes are moved.

This scaffold, called the spindle, forms at the beginning of mitosis under the direction of the centrioles. Sexual Reproduction Sexual reproduction is the mingling of the DNA of two different organisms of the same species to produce a cell, or cells, with a new combination of genes. When this occurs between single-celled organisms, it is called conjugation. In multi-cellular organisms, sexual reproduction requires the production of male and female germ cells by a process called meiosis. During this process a cell divides twice; but its chromosomes are duplicated only once.

Thus, four germ cells are produced, each containing half the normal number of chromosomes. In the male organism the germ cells develop into sperm; in the female they develop into eggs. A sperm and an egg then unite to form a new cell, called a zygote, that has a complete set of chromosomes and has received half its genetic information from each parent, thus making it a new individual. Differentiation Differentiation is the process by which a cell daughter becomes different from its parent in appearance or function, or both, even though both parent and daughter cell contain identical genetic information.

The appearance and function of identical daughter cells are initially specified by two kinds of information inherited by each in equal measure from the parent: cytoplasmic and nuclear information. Alterations in either kind of information will result in daughter cells being unlike their parents. Cytoplasmic information consists chiefly of cell organelles and messenger RNAs ready for translation into proteins, whereas nuclear information is contained in the genetic code.

Changes in cytoplasmic information generally are the result of unequal divisions that produce an asymmetrical distribution of cytoplasmic organelles and messenger RNAs between daughter cells. Changes in nuclear information involve restriction of the use of some portion of the cell’s genes, because genes can be turned on or off by the cell in response to cellular environmental signals. The behavior of a cell at any given time in differentiation largely depends on which subset of genes is turned on.

Differentiation primarily occurs through activation and deactivation of genes in a programmed succession to produce orchestrated changes in cell characteristics. During differentiation certain genes often are irreversibly turned off, and the change becomes permanent. This limits the variety of ways in which a cell can respond to an environmental signal, as well as the variety of signals to which it can respond, and the cell is channeled toward its ultimate differentiated fate. This process is called determination. Thus, a human nerve cell cannot transform into a human muscle cell even though they each contain identical genetic information.

Aging of cells is sometimes viewed as a continuation of their differentiation, with death seen as the final determination. Origin of Life and Evolution of Cells Scientists have formulated many theories about the origin of life and how it evolved into the various forms known today. These ideas are deduced from the evidence of the fossil record, from laboratory simulations of conditions on the primeval earth, and from consideration of the structure and function of cells. The earth was created more than 3 billion years ago, although more than 2 billion years probably passed before life as it is now known developed.

Scientists believe that the atmosphere of the young earth was mostly water vapor, methane, and ammonia, with very little gaseous oxygen. Laboratory simulations have shown that all major classes of organic molecules could have been generated from this atmosphere by the energy of the sun or by lightning and that the lack of oxygen would prevent newly formed organic molecules from being broken down by oxidation. Rain would have carried these molecules into lakes and oceans to form a primordial soup. When the concentration of organic molecules in this soup became high enough, molecules would have begun to form stable aggregates.

For example, lipids might coalesce into droplets the way cooking oil does in water, thus generating simple membranes and trapping other organic molecules in the interior of the droplet. Randomly formed aggregations that could harness energy to grow and reproduce themselves would eventually far outnumber other combinations. DNA may have been an essential component of the self-reproducing aggregates; it and RNA are the only organic molecules able to duplicate themselves. These supramolecular aggregations would have been extremely lifelike and with some refinements would have resembled primitive prokaryotes.

This concept of the origin of life, however, does not explain the development of the genetic code and the precise interdependence between the code and protein synthesis. The relative absence of oxygen from the atmosphere of the young earth meant that no ozone layer existed to screen out ultraviolet radiation and no oxygen was available for aerobic respiration. Therefore, the first cells were probably photosynthetic and used ultraviolet light. Because photosynthesis generates oxygen, the oxygen content of the atmosphere gradually increased.

As a result, cells that could use this oxygen to generate energy, and photosynthetic cells that could use light other than ultraviolet, eventually became predominant. Eukaryotes may have evolved from prokaryotes. This idea comes from speculation about the origin of mitochondria and chloroplasts. These organelles may be the degenerate descendants of aerobic and photosynthetic prokaryotes that were engulfed by larger prokaryotes but remained alive within them. Over the years the host cell became dependent on the endosymbionts for energy (ATP), while they in turn became dependent on the host for most other cell functions.

The fact that mitochondria and chloroplasts are surrounded by two membranes, as if they had originally entered the cell by phagocytosis, supports this theory. In addition, these organelles contain their own DNA and ribosomes, which resemble the DNA and ribosomes of bacteria more than those of eukaryotes. It is possible that other eukaryotic organelles originated similarly. History Cells were first described in 1665 by the English scientist Robert Hooke, who studied the dead cells of cork with a crude microscope.

Living cells were first described in detail in the 1670s by the Dutch scientist Anton van Leeuwenhoek. These early descriptions were not improved on until the early 19th century, when better-quality microscope lenses were developed. In 1839 the German botanist Matthias Schleiden and the German zoologist Theodor Schwann formulated the basic cell theory of today. Struck by the underlying similarity between plant and animal cells, they stated that all living organisms consist of cells and cell products. Thus, a whole organism could be understood through the study of its cellular parts.

In 1858 the German pathologist Rudolf Virchow’s theory, that all cells come from preexisting cells, led to the development of ideas about cell division and cell differentiation. The development in the late 19th century of techniques for staining cell parts enabled scientists to detect tiny cell structures that were not actually seen in detail until the advent of the electron microscope in the 1940s. The development of various advanced optical techniques in the 20th century also increased the detection power of the light microscope for observations of living cells.

The study of cells is not limited to describing structures. A central concept in modern cytology is that each structure has a function that may be understood as a series of biochemical reactions. The understanding of these functions has been greatly aided by the development of cell fractionation techniques, using an ultracentrifuge to separate specific intracellular structures from the rest of the cell. Another technique is tissue culture, by which specific kinds of cells can be isolated and grown for study.

How many different jobs are there and what education is needed? I decided to do a report on Marine Mammal Biology. I have a deep interest in this subject and one day would like to pursue a career in Marine Mammal Biology. There are about 100 species of aquatic or marine mammals that depend on fresh water or the ocean for part or all of their life. These species include Pennipeds (seals), sea lions, fur seals, and walruses, Cetaceans (baleen and toothed whales, ocean and river dolphins and porpoises), Sirenians which are manatees.

Scientists try to study there animals genetic, systematic, and evolutionary relationships, population structure, community dynamics, anatomy and physiology, behavior and sensory abilities, diseases, geographic distributions, ecology, management, and conservation. The average salary a biologist makes a year ranges depends on the amount of experience one has. Most biologists make 30,000-40,000 a year. The work is usually back breaking and long hours out on the sea, extensive work on the computer, hauling buckets of fish to feed the animals, hours of clean-up, numerous reports, typing grant applications and permit applications.

In fields of science, jobs dealing with marine mammals vary widely. Marine mammal jobs include researcher, field biologist, fishery vessel observer, laboratory technician, animal trainer, animal care specialist, veterinarian, whale watch guide, naturalist, educator, and government or private agency position in legislative, management, conservation, and animal welfare issues. Many marine mammals scientists work with museum displays and collections, as a curator, an artist, an illustrator, a photographer, or a filmmaker. A broad education is necessary for finding employment in marine mammal science.

High school courses such as biology, chemistry, physics, mathematics, computer science, and language, will provide a good educational base. You can talk to a guidance counselor for help in selecting course work. Good grades are important for admission to a university. Most entry-level marine mammal jobs require a B. S. degree, with a major in biology, chemistry, physics, geology, or psychology. A minor in any science, computer science, mathematics, statistics, or engineering also can be helpful. Good language and technical writing skills are essential.

Many people are surprised by the amount of writing involved marine mammal professions. Because marine mammals are found worldwide, foreign language training is often useful. The masters degree is usually the first opportunity that college students have to specialize in marine mammal science. Care should be taken to select an advisor with experience in the subject and a reputable university with a diverse curriculum that will enable a focus on marine mammal science. Students who have dual majors or interdisciplinary training sometimes have more employment opportunities.

Because the field of marine mammal science is so diverse, students who train in specialized areas have practical tools that may help them gain employment. With a B. S. degree, positions include animal care specialist, animal trainer, field technician, laboratory technician, consultant for industry, and entry-level government position. Jobs at this level offer little opportunity for self-directed work. The M. S. degree can facilitate individual work with marine mammals, like designing research projects, developing management plans, supervising field or laboratory studies, or heading programs in education, husbandry, or training.

The acquisition of a Ph. D. or D. V. M. provides more career opportunities, including design and management of field and laboratory research programs, university faculty positions, coordination of government and industry programs, and management positions in oceanaria or museums. There are very few universities that offer a marine mammal science curriculum. To select an undergraduate university, visit campuses and talk with professors and students about career interests. Most university libraries or counseling centers have university catalogs to look up schools who can provide you the classes you need.

As a high school or undergraduate student, practical experience can be gained by volunteering at federal, state, or local organizations that work with marine mammals. This volunteer experience provides practical skills, an employer reference, a network of contacts in the field of marine mammal science, and most importantly helps determine whether this type of work is appealing. Many oceanaria, zoos, museums, and government agencies have internships that provide practical experience.

Many careers in marine mammal science require experience in the marine environment. SCUBA certification, boat-handling experience, or sea time can be helpful in securing employment in the field of marine mammal science. Often a good source for job announcements is the personal department of a specific agency. The journal Science and The Chronicle of Higher Education list academic position junior colleges, colleges and universities. In conclusion I hope you learned something about marine mammal science. I also hope you found it interesting.

Synthesis is the process of producing a chemical compound usually by the union of simpler chemical compounds. For example, photosynthesis, the word photo means putting together with light. Photosynthesis is the process of converting sunlight into food for organic organisms such as plants. Photosynthesis is the basis of life for planet earth and without it; not only would we not be able to produce the fruits and vegetables that we consume, but the food to feed the animals that we eat. Plants absorb this sunlight which in turn makes oxygen in a process called respiration.

This delicate cycle is what allows us to thrive on this planet. Although much of the life on this planet relies on photosynthesis in one way or another, there is another form of synthesis that is equally as important, chemosynthesis. The deep sea is considered the largest, yet, least-known habitat on earth and covers about two-thirds of the earth. Every year, and every dive down to the mysterious depths of the deep-sea bring scientist closer and closer to unraveling the secrets of the unimaginable deep.

This is where chemosynthesis takes place because there is no sunlight available in order for photosynthesis to take place. How hydrothermal vents work In 1977, in the Galapagos Islands, the first hydrothermal vents were found. Using a submersible called the Alvin, scientist were able to explore this alien world never known to have existed for the first time. Hydrothermal vents are chimney like structures on the ocean floor that release extremely hot, mineral rich water. This process is called Hydrothermal Circulation. Ocean water seeps into the earth, becoming increasingly hotter as it descends downward.

As the water passes through the cracks of the earth, it is becoming enriched with metals and minerals until finally turning to a very acidic fluid. When the super heated water reaches about 700˚F (400˚C), the fluid rises and bursts through cracks in the sea floor. The super heated water mixing with the cold sea water causes a chemical reaction and forms particles of metal sulfide to cloud the water. The pieces of metal settle around the area of the crack, and over time, collect to form the chimneys of black smokers.

One would assume that at the very bottom of the ocean, in 700˚F waters, that nothing could possibly exist here. Surprisingly, over 300 strange and unique species thrive only in these conditions. What lives near hydrothermal vents? Although hydrothermal vent habitats would be considered a harsh habitat for life to thrive, oddly, a collection of animals live near hydrothermal vents. Animals living here have to deal with the high pressure, steep temperature gradients, and the extremely high concentrations of toxic elements such as sulfides and metals (Minic & Herve, 2003).

Clams, mussels, crabs, and worms are found near hydrothermal vent locations (Grassle, 1985). Normally, deep sea soft bottoms are characterized by low population densities, high species diversity and low biomass. But, in the case of chemosynthetic hydrothermal vent communities, this is not true. Since there isn’t anything on the sea floor, other than hydrothermal vents, the area surrounding a vent exhibit high densities and biomass, low species diversity, rapid growth, and high metabolic rates (Corselli & Basso, 1995).

How hydrothermal vent creatures survive Earlier, photosynthesis; the production of food using light, was discussed. How do creatures who live in hydrothermal vent communities and other areas devoid of sunlight make food? They use a process called chemosynthesis. Chemo- means chemical, and as previously stated, synthesis means the process of producing a chemical compound usually by the union of simpler chemical compounds, thus, Chemosynthesis must mean the process of converting chemicals into food.

In order for one to understand the chemosynthesis, you must know the why, where and how of it. Why: Animals found near hydrothermal vents have very few options for food. They either have the chemosynthetic bacteria to perform chemosynthesis, or they wait for some type of carcass to slowly drift to the bottom of the ocean. Without chemosynthesis, most animals near hydrothermal vents would not be able to live. Where: Chemosynthesis can only occur where there is lack of sunlight with the proper bacteria and chemicals needed to perform chemosynthesis.

Plants evolved more than 430 million years ago from multicellular green algae. By 300 million years ago, trees had evolved and formed forests, within which the diversification of vertebrates, insects, and fungi occurred. Roughly 266,000 species of plants are now living. The two major groups of plants are the bryophytes and the vascular plants; the latter group consists of nine divisions that have living members. Bryophytes and ferns require free water so that sperm can swim between the male and female sex organs; most other plants do not.

Vascular plants have elaborate ater- and food conducting strands of cells, cuticles, and stomata; many of these plants are much larger that any bryophyte. Seeds evolved between the vascular plants and provided a means to protect young individuals. Flowers, which are the most obvious characteristic of angiosperms, guide the activities of insects and other pollinators so that pollen is dispersed rapidly and precisely from one flower to another of The same species, thus promoting out crossing. Many angiosperms display other modes of pollination, including self-pollination.

Evolutionary Origins Plants derived from an aquatic ancestor, but the evolution of their onducting tissues, cuticle, stomata, and seeds has made them progressively less dependent on water. The oldest plant fossils date from the Silurian Period, some 430 million years ago. The common ancestor of plants was a green alga. The similarity of the members of these two groups can be demonstrated by their photosynthetic pigments (chlorophyll a and b,) carotenoids); chief storage product (starch); cellulose- rich cell walls (in some green algae only); and cell division by means of a cell plate (in certain green algae only).

Major Groups As mentioned earlier, The two major groups of plants are The bryophytes- mosses, liverworts, and hornworts–and The vascular plants, which make up nine other divisions. Vascular plants have two kinds of well-defined conducting strands: xylem, which is specialized to conduct water and dissolved minerals, and phloem, which is specialized to conduct The food molecules The plants manufacture. Gametophytes and Sporophytes All plants have an alternation of generations, in which haploid gametophytes alternate with diploid sporophytes.

The spores that sporophytes form as a result of meiosis grow into gametophytes, which produce gametes–sperm and eggs–as a result of mitosis. The gametophytes of bryophytes are nutritionally independent and remain green. The sporophytes of bryophytes are usually nutritionally dependent on The gametophytes and mostly are brown or straw-colored at maturity. In ferns, sporophytes and gametophytes usually are nutritionally independent; both are green.

Among The gymnosperms and angiosperms, The gametophytes are nutritionally dependent on the sporophytes. In all seed plants–gymnosperms and angiosperms–and in certain lycopods and a few ferns, the gametophytes are either female (megagametophytes) or male (microgametophytes). Megagametophytes produce only eggs; microgametophytes produce only sperm. These are produced, respectively, from megaspores, which are formed as a result of meiosis within megasporangia, and microspores, which are formed in a similar fashion within microsporangia.

In gymnosperms, the ovules are exposed directly to pollen at the time of pollination; in angiosperms, the ovules are enclosed within a carpel, and a pollen tube grows through the carpel to the ovule. The nutritive tissue in gymnosperm seeds is derived from the expanded, food-rich gametophyte. In angiosperm seeds, the nutritive tissue, endosperm, is nique and is formed from a cell that results from the fusion of the polar nuclei of the embryo sac with a sperm cell.

The pollen of gymnosperms is usually blown about by the wind; although some angiosperms are also wind-pollinated, in many the pollen is carried from flower to flower by various insects and other animals. The ripened carpels of angiosperm grow into fruits, structures that are as characteristic of members of the division as flowers are.  Gymnosperms Gymnosperms are non-flowering plants. They also make up four of the five divisions of the living seed plants, with angiosperms being the fifth.

In gymnosperms, the ovules are not completely enclosed by the tissues of the sporophytic individual on which they are borne at the time of pollination. Common examples are conifers, cycads, ginkgo, and gnetophytes. Fertilization of gymnosperms is unique. The cycad sperm, for example, swim by means of their numerous, spirally arranged flagella. Among the seed plants, only the cycads and Ginkgo have motile sperm. The sperm are transported to the vicinity of the egg within a pollen tube, which bursts, releasing them; they then swim to the egg, and fertilize it.

Angiosperms The flowering plants dominate every spot on land except for the polar regions, the high mountains, and the driest deserts. Despite their overwhelming success, they are a group of relatively recent origin. Although they may be about 150 million years old as a group, the oldest definite angiosperm fossils are from about 123 million years ago. Among the features that have contributed to the success of angiosperms are their unique reproductive features, which include the flower and the fruit.

Angiosperms are characterized primarily by features of their reproductive system. The unique structure known as the carpel encloses the vules and matures into the fruit. Since the ovules are enclosed, pollination is indirect. History The ancestor of angiosperms was a seed-bearing plant that was probably already pollinated by insects to some degree. No living group of plants has the correct combination of characteristics to be this ancestor, but seeds have originated a number of times during the history of the vascular plant.

Although angiosperms are probably at least 150 million years old as a group, the oldest definite fossil evidence of this division is pollen from the early Cretaceous Period. By 80 or 90 million years ago, angiosperms were more ommon worldwide that other plant groups. They became abundant and diverse as drier habitats became widespread during the last 30 million years or so. Flowers and Fruits Flowers make possible the precise transfer of pollen, and therefore, outcrossing, even when the stationary individual plants are widely separated.

Fruits, with their complex adaptations, facilitate the wide dispersal of angiosperms. The flowers are primitive angiosperms had numerous, separate, spirally arranged flower parts, as we know from the correlation of flowers of this kind with primitive pollen, wood, and other features. Sepals are homologous with eaves, the petals of most angiosperms appear to be homologous with stamens, although some appear to have originated from sepals; and stamens and carpels probably are modified branch systems whose spore-producing organs were incorporated into the flower during the course of evolution.

Bees are the most frequent and constant visitors of flowers. They often have morphological and physiological adaptations related to their specialization in visiting the flowers of particular plants. Flowers visited regularly by birds must produce abundant nectar to provide the birds with enough energy so theat they will continue to be attracted o them. The nectar visited plants tends to be well protected by the structure of the flowers. Fruits, which are characteristic of angiosperms, are extremely diverse.

The evolution of structures in particular fruits that have improved their possibilities for dispersal in some special way has produced many examples of parallel evolution. Fruits and seeds are highly diverse in terms of their dispersal, often displaying wings, barbs, or other structures that aid their dispersal. Means of fruit dispersal are especially important in the colonization of islands or other distant patches of suitable habitat.

With the ever-increasing problem of pest control, it is clear that some form biological must be implemented in order to help farmers. This biological control must be able to effectively control the pest population, this means not killing them but rather never letting the pest populations get too large. Through computer-simulated programs the Spider Division of Frankenstein, Inc. was able to genetically create a spider that genetically perfect for biological control. This paper will discuss the methods that were taken as well as the results of the Spider Divisions experiment. Introduction

Biological control is an important factor if we are to protect and increase our crop production. This paper outlines an experiment that was done by the Spider division of Frankenstein, Inc, in their attempt to create a new and improved form of biological control. The experiment purpose is to genetically manufacture the perfect spider for biological control, the spider will be known as the Paine Killer Spider, which will be genetically perfect for its environment. The genetic factors of the spiders’ eyesight, how fast it moves, and how fast it reproduces will be crucially important in its development.

These three factors will set the parameters for how well the Paine Killer Spider will perform in its ecosystem. Besides the biological factors, how well the spider interact with other predators, as well as its natural enemies must also be taken in account. For this experiment, the Spider division of Frankenstein, Inc. did extensive research through Ecological journals with subjects on all types of biological control. Through the Eco Beaker simulation the team at the Spider Division will show that a genetically created spider can and will be successful for biological control purposes.

This Eco Beaker simulation effectively simulates the introduction of an insect into an ecosystem for biological control purposes. Materials and Methods In creating the Paine killer Spider, the Eco Beaker simulator proved to be a easy and useful way of a conducting the experiment. By randomly selecting parameters for the spiders eyesight, speed, and reproduction the Spider Division was we able to come up with numbers that would stabilize the ecosystem and allow for the genetically produced spider and aphids to live together harmoniously.

In a matter of hours the Spider Division was able to come up with a set of parameters for the Paine Killer Spider that would allow for perfect biological control. While there could be numerous different combinations that could work for the different parameters, the Spider division found that the Paine Killer Spiders parameters should be set at; 1 meter for sight; 1. 9 meters per day for speed; and a reproduction rate of 1 spider per 2. 2 aphids. With these parameters the Paine Killer Spider will have a successful introduction into its ecosystem.

Results The Eco Beaker system clearly demonstrated that the Spider Division is capable of producing the “perfect” spider. By mixing in different combinations if genetic parameter, the Eco Beaker system was able to show the negative effects of having to much or little speed, too much or too little eyesight, and too fast or too slow of a reproduction system. By coming up with the combination listed above, the Spider Division clearly demonstrated that the Paine Killer Spider would be able to adapt to its environment and control the aphid population.

It will also be able for long periods of time. While this experiment was designed to examine a yearlong period, the Spider Division decided to extend it for three years. The chosen parameters enabled the Paine Killer Spider to control the environment for the whole three years on the Eco Beaker simulator. Through the simulator the spider was very successful in a large crop field, but is very feasible that the spider could be even more successful in a field that is broken up into small sections separated by streams or other barriers.

Discussion Why dont farmers just use more pesticides? With aphids continually adapting to pesticides it just not cost effective for the farmers to rely on these pesticides. Framers find themselves losing money and crops in trying to beat the aphids to the punch. Therefore biological control can be a very effective way to control the aphid population. Clearly this experiment shows that genetically manufactured spider can be very successful in controlling its environment and maintaining an acceptable aphid population.

This sort of biological control may very well be the wave of the future. It almost allows for nature and not chemicals to control its own environment, even though this nature is genetically manufactured. In conclusion, this experiment shows that the “perfect” spider can be produced. By genetically altering it speed, eyesight, and reproduction rate Frankenstein, Inc. can create the ultimate form of biological control. It is clear that the Paine Killer Spider is just the tip of the iceberg for biological control.

With the ever-increasing problem of pest control, it is clear that some form biological must be implemented in order to help farmers. This biological control must be able to effectively control the pest population, this means not killing them but rather never letting the pest populations get too large. Through computer-simulated programs the Spider Division of Frankenstein, Inc. was able to genetically create a spider that genetically perfect for biological control. This paper will discuss the methods that were taken as well as the results of the Spider Divisions experiment.

In order to carry on photosynthesis, green plants need a supply of carbon dioxide and a means of disposing of oxygen. In order to carry on cellular respiration, plant cells need oxygen and a means of disposing of carbon dioxide (just as animal cells do). Unlike animals, plants have no specialized organs for gas exchange. The are several reasons they can get along without them. Each part of the plant takes care of its own gas exchange needs. Although plants have an elaborate liquid transport system, it does not participate in gas transport.

Roots, stems, and leaves respire at rates much lower than are characteristic of animals. Only during photosynthesis are large volumes of gases exchanged and each leaf is well adapted to take care of its own needs. The distance that gases must diffuse in even a large plant is not great. Each living cell in the plant is located close to the surface. While obvious for leaves, it is also true for stems. The only living cells in the stem are organized in thin layers just beneath the bark. The cells in the interior are dead and serve only to provide mechanical support.

Most of the living cells in a plant have at least part of their surface exposed to air. The loose packing of parenchyma cells in leaves, stems, and roots provides an interconnecting system of air spaces. Gases diffuse through air several thousand times faster than through water. Once oxygen and carbon dioxide reach the network of intercellular air spaces, they diffuse rapidly through them. The exchange of oxygen and carbon dioxide in the leaf (as well as the loss of water vapor in transpiration) occurs through pores called stomata (singular = stoma).

Normally stomata open when the light strikes the leaf in the morning and close during the night. The immediate cause is a change in the turgor of the guard cells. The inner wall of each guard cell is thick and elastic. When turgor develops within the two guard cells flanking each stoma, the thin outer walls bulge out and force the inner walls into a crescent shape. This opens the stoma. When the guard cells lose turgor, the elastic inner walls regain their original shape and the stoma closes.

Woody stems and mature roots are sheathed in layers of dead cork cells impregnated with suberin – a waxy, waterproof (and airproof) substance. So cork is as impervious to oxygen and carbon dioxide as it is to water. However, the cork of both mature roots and woody stems is perforated by nonsuberized pores called lenticels. These enable oxygen to reach the intercellular spaces of the interior tissues and carbon dioxide to be released to the atmosphere. In many annual plants, the stems are green and almost as important for photosynthesis as the leaves. These stems use stomata rather than lenticels for gas exchange.

Biology is the study of living things. Biology also includes the study of humans at the molecular, cellular. If the focus of investigation is the application of biological knowledge to human health, the study is often termed biomedicine. Molecular Biology is the research that seeks to understand the molecular basis of life.

In particular it relates the structure of specific molecules of biological importance-such as proteins, he nucleic acids DNA and RNA, and enzymes, to their functional role in the intact cell and organism. There are many branches of biology. Some of them are: Zoologists, botanists, entomologist and microbiologist. Zoologists are concerned with animals and botanists with plants. Entomologist’s study insects while a microbiologist works with living things that are too small to see without help of a microscope.

What are biological species? At first glance, this seems like an easy question to answer. Homo sapiens is a species, and so is Canis familaris (dog). Many species can be easily distinguished. When we turn to the technical literature on species, the nature of species becomes much less clear. Biologists offer a dozen definitions of the term “species”. These definitions are not fringe accounts of species but prominent definitions in the current biological literature. Philosophers also disagree on the nature of species. Here the concern is the ontological status of species. Some philosophers believe that species are natural kinds.

Others maintain that species are particulars or individuals. The concept of species plays an important role both in and outside of biology. Because of the important role of this concept, many biologists proposed definitions for this concept. Over the last few decades, the Biological Species Concept (BSC) has become predominately the dominant species definition used in biology. This concept defines a species as a reproductive community. This though has had much refinement through the years. The earliest precursor to the concept is in Du Rietz (1930) then later Dobzhansky added to this definition in 1937.

But even after this the definition was highly restrictive, the definition of a species that is accepted as the Biological Species Concept was founded by Ernst Mayr; “… groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups”. However, this is a definition on what happens in nature. Mayr later amended this definition to include an ecological component; “… a reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature. The BSC is greatly accepted among vertebrate zoologists and entomologists.

Two reasons account for this addition to the definition of Biological Species Concept. Firstly, these are the groups that the authors of the BSC worked with (Mayr is an Ornithologist & Dobzhansky has worked mainly with Drosophila). More importantly, Sexual reproduction is the predominate form of reproduction in these groups. It is not coincidental that the BSC is less widely used amongst botanists. Terrestrial plants exhibit much greater diversity in their mode of reproduction than vertebrates and insects. There have been many criticisms of the BSC in its theoretical validity and practical utility.

For example, the application of the BSC to a number of groups is problematic because of interspecific hybridization between clearly delimited species. It can’t be applied to species that reproduce asexually (e. g. Bdelloid rotifers, eugelenoid flagellates). Asexual forms of normally sexual organisms are also known. Prokaryotes are also left out by the concept because sexuality as defined in the eukaryotes is unknown (Society for Developmental Biology, 1955). The Biological Species Concept is also questionable in those land plants that primarily self-pollinate. Practically the BSC has its limitations in the most obvious form of fossils.

It can’t be applied to this evolutionary distinct group because they no longer mate. It also has limitations when practically applied to delimit species. The BSC suggests breeding experiments as the test of whether an organism is a distinct species. But this is a test rarely made, as the number of crosses needed to delimit a species can be massive. Thus, time, effort, and money needed to carry out such tests that are prohibitive. Not only this but also the experiment carried out are often inconclusive. In practice even strong believers of the BSC use phenetic similarities and discontinuties for delimiting species.

Although more widely known, several alternatives to the Biological Species Concept exist. The Phenetic (or Morphological / Recognition) Species Concept proposes an alternative to the BSC that has been called a “renewed practical species definition”. This defines species as; “… the smallest groups that are consistently and persistently distinct and distinguishable by ordinary means. ” Problems with this definition can be seen, once again depending on the background of the user. For example “ordinary means” includes any techniques that are widely available, cheap and relatively easy to apply (Kerry L. Shaw, 2002).

These means will differ among different groups of organisms. For example, to a botanist working with angiosperms ordinary means might mean a hand lens; to an entomologist working with beetles might mean a dissecting microscope; to a phycologist working with diatoms, it might mean a scanning electron microscope. What means are ordinary are determined by what is needed to examine the organisms in question. Thus, once again we see that it is a subjective view depending on how the biologist wants to read the definition. It also has similar difficulties to the BSC in defining between asexual species and existence of hybrids.

There are several phylogenetic species definitions. All of them suggest hat classifications should reflect the best supported hypotheses of the phylogeny of the organisms. The biologist Baum described two types of phylogenetic species concepts, one of thes is that a species must be monophyletic and share one or more derived character. There are two meanings to monophyletic according to the scientist Mayr. The first defines a monophyletic group as all the descendants of a common ancestor and the ancestor. The second defines a monophyletic group as a group of organisms that are more closely related to each other than to any other organisms.

The species concepts are only theoretical and by no means no standard as to which species should be grouped (Ernst Mayr, 1996). However, it can be argued that without a more stuructured approached proper discussion can not occur due to conflicting species names. And so, if there are quite large problems with all of the species concepts, the question about what is used in practicehas to be asked. Most taxonomists use one or more of four main criteria. The first one is the individuals should bear a close resemblance to one another such that they are always readily recognisable as members of that group.

The second criterion, there are gaps between the spectra of variation exhibite by related species; if there are no such gaps then there is a case for amalgamating the taxa a single species. Also, each species occupies a definable geographical area (wide or narrow) and is demonstrably suited to the environmental conditions which it encounters. Lastly, in sexual taxa, the individuals should be capable of interbreeding with little or no loss of fertility, and there are should be some reduction in the level or success (measured in terms of hybrid fetility or competitiveness) of crossing with other species.

Of course, as has been seen, no one of these criteria is absolute and it is more often left to the taxonomists own judgement. Quite frequently a classification system is brought about from the wrong reasons. Between two taxa similarities and differences can be found which have to be considered, and it is simply up to the taxonomists’ discretion as to which differences or simila rities should be empahasised. Thus, differences are naturally going to arise between taxonomists.

The system used can be brought about for convienience, from historical aspects and to save argument. It may be a lot easier to stick with a current concept, although requiring radical changes because of the upheaval and confusion that may be caused. As seen much has been written on the different concepts and improvements to these concepts but these amounts to little more than personal judgements aimed at producing a workable classification (Mann D. G. 1989).

In general most Biologists adopt the definition of species that is most suited to the type of animal or plant that they are working with at the time and use their own judgement as to what that means. It is common practice amongst most taxonomists to look for discontinuities in variation which can be used to delimit the kingdoms,divisions etc.. Between a group of closley related taxa it can be useful, although highly subjective, to use the crtieria of equivalence or comparibility. Usually however, the criteria of discontinuity are more accurate than comparability, even if the taxa are widely different.

Plants are critical to other life on this planet because they form the basis of all food webs. Most plants are autotrophic, creating their own food using water, carbon dioxide, and light through a process called photosynthesis. Some of the earliest fossils found have been aged at 3. 8 billion years. These fossil deposits show evidence of photosynthesis, so plants, or the plant-like ancestors of plants, have lived on this planet longer that most other groups of organisms. At one time, anything that was green and that wasnt an animal was considered to be a plant.

Now, what were once considered plants are divided into several kingdoms: Protista, Fungi, and Plantae. Most aquatic plants occur in the kingdoms Plantae and Protista. It is believed that the earth was originally an aggregation of dust and swirling gases about 4. 5 billion years ago. The earliest fossil life forms are 3. 8 billion years old and contain simple prokaryotic (without a membrane-bound nucleus) cells. The atmosphere at that time was mostly nitrogen gas, with large portions of carbon dioxide and water vapour.

Since life evolved in this atmosphere, carbon, oxygen, hydrogen, and nitrogen (major elements of nitrogen gas, carbon dioxide and water) make up 98% of the organic materials in living organisms. There was no oxygen in the early atmosphere, so all life existed in an anaerobic environment. Since no human was alive to document the events of the early earth, much of our information has been pieced together from studies of the fossil record. It is now believed that the earth 4. billion years ago was a very tumultuous place; there were violent electrical storms, radioactive substances emitting large quantities of energy, and molten rock and boiling water erupting from beneath the earths surface. These forces broke apart the simple gases in the atmosphere, causing them to reorganize into more complex molecules. Ultraviolet light bombarded the surface of the earth, breaking apart the complex molecules and forming new ones. These complex compounds were washed out of the atmosphere by driving rains and subsequently collected in the oceans.

Many organic molecules tend to clump together, so the early oceans probably had aggregations of organic molecules that looked like droplets of oil in water. These clusters of molecules may have been the ancestors of primitive cells. They may also have been the source of energy for early life forms; primitive cells could have used these complex compounds to satisfy their energy requirements. As these early heterotrophs increased in number, the aggregations of complex organic molecules started to become depleted. It became more and more difficult to find food, so competition between cells commenced.

Eventually cells evolved that could make their own food from simple inorganic materials. The most successful of these early autotrophs were those that could use solar energy to create their own energy; those that could photosynthesize. They used a complex pigment system to capture and hold light energy in the form of organic molecules. Why are plants so important? If plants hadnt evolved to photosynthesize, life on this planet would be very different. Plants produce their food by photosynthesis, and the most important waste product of this process is oxygen – something that most of the animal life on this planet cant live without!

As the first plants began photosynthesizing, the amount of oxygen in the atmosphere increased. Some of the oxygen in the outer layer of the atmosphere was converted to ozone. Eventually there was enough ozone in the upper atmosphere to effectively filter out the harmful ultraviolet rays that are highly destructive to living organisms. This allowed organisms to survive in the surface layers of water and on land. Having an abundant supply of oxygen in the atmosphere also allowed other organisms to break down the complex energy-containing molecules formed by photosynthesis by a more efficient pathway called respiration.

This yields much more energy that can be obtained in an atmosphere without oxygen Early life was found in the surface waters of the open ocean. As life became more abundant, essential resources were depleted. So, life became more abundant in areas where there were renewable resources, primarily near shores. The rains and waterways carried nitrates and minerals from the mountains and into the water where they were available for the early plants to use. The differentiated coastline also provided a complex habitat where specialization gave some plants a competitive edge over others in that habitat.

Water Hyacinth (Eichornia crassipes) is a troublesome aquatic weed and has spread in almost all lakes, ponds and river in the entire tropical world. Attention has been focused on its environmental impact since its luxuriant growth in the water bodies interferes in the activities of mankind, which has caused great concern. Its widespread occurrence in the fresh water lakes and riverbeds is proving detrimental to fishing rowing and depleting water content from the water bodies and interfering in water utilization and other activities.

The rapidly proliferating water hyacinth clogs waterways, irrigation channels, drains and affect navigation, fishing, fish spawning etc. in Kerala State. Water hyacinth is a microphyte and is rich in cellulose content, which can be used as renewable source of energy. The use of fermentation technology for the production of value added chemicals from lignocelluloses holds great promise. It is proposed to set up a pilot plant with a new technology developed by National Environmental Engineering Research Institute (NEERI), Nagpur for conversion of Cellulase from Water Hyacinth.

If found successful, this will be replicated in various locations of the State, which will help the environmentalists to succeed in the battle to eradicate this menace for the past two decades. Seaweeds are large algae (macroalgae) that grow in a saltwater or marine environment. Seaweeds are plants, although they lack true stems, roots, and leaves. However, they possess a blade that is leaflike, a stipe that is stemlike, and a holdfast that resembles a root. Like land plants, seaweeds contain photosynthetic pigments (similar to chlorophyll) and use sunlight to produce food and oxygen from carbon dioxide and water.

Embryonic stem cell research is widely controversial in the scientific world. Issues on the ethics of Embryonic Stem (ES) cell research have created pandemonium in our society. The different views on this subject are well researched and supportive. The facts presented have the capability to support or possibly change the public’s perspective. This case study is based on facts and concerns that much of the research done on embryonic stem cells is derived from human embryos.

This case study will provide others with a more in depth view of both sides of this great debate. In biological terms, embryonic stem cells posses a virtually unlimited future. “Adult stem cell research has produced results that could help many patients with various diseases, but proponents of embryonic stem cell research argue that the progress in adult stem cell research should not preclude embryonic stem cell research” (Kukla, 2002). As of November 2004, California residents voted “yes” to approve $3 billion dollars for stem cell research.

Michelle Lane, who is the state coordinator for the Parkinson’s Action Network in Louisiana, was not only relieved to see this go through but because she has early on-set signs of Parkinson’s disease she says “It proves we can win this battle. ” Kalb, C. (2004) Scientists believe that using embryonic stem cells offers the most possibilities in scientific research; these cells have the capability to develop into any of the 210 cells found in the human body including heart cells, nerve cells, muscle cells, and skin cells.

The budding capacity of the embryonic stem cell may prove useful for treatment of some medical conditions including Alzheimer’s and Parkinson’s disease, diabetes, spinal cord injuries, heart disease and cancer. The prospective advantage of using embryonic stem cells is fascinating. Embryonic stem cells are capable of becoming any cell type in the body making them more versatile than adult stem cells. There is a possibility that the patient’s body can reject the adult cells because their derivative is from cells that are not a patient’s own.

Supporters of research state that stem cells from embryos are acceptable for research since the embryos are not considered to be human and is vital to the possible future cure of some debilitating diseases including Alzheimer’s and paraplegia. Researchers justify their work by stating the benefits out weigh the arguments against doing the research and do not consider the embryos to be human beings. Researchers have stated that while the embryos have cells like living human beings, they themselves are not human.

A belief as such, justifies embryonic stem cell research for those who perform or support it. The use of private funding has uncovered the existent of more than sixty genetically diverse stem cell lines. The use of federal funds for research on these existing sixty stem cell lines, where the life and death decision has already been made would allow us to explore the promise and potential of stem cell research without crossing a fundamental moral line by providing taxpayer funding that would sanction or encourage further destruction of human embryos that have at least the potential for life.

Based on preliminary work that has been mainly funded privately, scientists believe further research using stem cells offers great promise that could improve the lives of those who suffer from many terrible diseases — from juvenile diabetes to Alzheimer’s, from Parkinson’s to spinal cord injuries. Adequate funding for embryonic stem cell research will allow scientist to discover more possibilities of what stem cells are capable of doing.

These possibilities include drug testing and cell-based therapies that cover a wide range of applications; differentiating into desired cell-types, generating sufficient quantities of tissue, and survival of the cells and recipient after the transplant. “No benefits from embryo stem can possibly outweigh the moral cost of destroying human life”, (Center for Bioethics and Human Dignity, 2002) the definition of when a life begins is unclear. This creates the ethical issue of destroying a life for research that possibly can save lives.

To destroy a life is ethically wrong no matter what the gain from it may be. “The duty to heal the sick cannot override the moral imperative to treat human beings as subjects and not objects. ” (Landry, D. & Zucker, H. 2004). “The ethical question forms the real root of the stem cell debate, specifically the question of the moral status of the human embryo. Scientifically and genetically, the embryo is a human being, its species is Homo sapiens, and the organism already has a gender. ” Prentice, D. (2003)

With the seemingly infinite uses for embryonic stem cell, the fact remains whether the morality of using ES cells for research is ethical. “Embryonic stem cells are harvested either by abandoned fertilized eggs left over from fertility clinics or the abortion of a five to nine-week old fetus. ” (Saltzman, 2001) In the process of harvesting these ES cells, the blastocysts are destroyed. “However, federal law and the laws of many states specifically protect vulnerable human embryos from harmful experimentation. (Center for Bioethics and Human Dignity, 2002) “There are ways to avoid abortions and embryos as a stem cell source by regressing adult cells. ” (Saltzman, 2001) While this method may take a little longer, it does not harm human life in the process. Who has the right to decide whether one life is more valuable than the other is? These embryos will develop into a human being given the chance, and they deserve the same right to respect as anyone else. As members of society, opponents should request that scientists answer the questions about the embryos species being human beings.

Supporters of the stem cell research state stem cells from embryos are acceptable for research since the embryos are not considered to be human. Researchers do not consider the embryos to be human beings and have failed to prove when life begins. Opponents of embryonic stem cell research state that life begins at conception. If this is true, the embryos should have all the rights our government gives to every other human being. Opponents want the government to protect the embryos’ right to life.

Opponents have suggested that all experiments and government funding toward this research be halted until scientists produced evidence, to support their position that embryos are not human. “The science of stem cell research is currently moving at such a rapid pace that moral language and experience cannot keep up. ” (Center for Bioethics and Human Dignity, 2002) While it is important to make medical strides, it is just as important that we know and understand the actual cost to achieve these strides.

There are ways to attain results that are beneficial to prolonging the ailing that do not include destroying the lives potential humans. The human race as a whole has much to gain from embryonic stem cell research. Advances in finding cures for currently incurable diseases are closely approaching and stem cells may be the key to these cures. Society has an obligation to look at the pros and cons surrounding the issue and the decisions being made about embryonic stem cell research. Society cannot take this issue lightly since a human life is at the center of this debate.

Researchers have an obligation according to the opponents to prove that embryos are not human beings. Opponent’s state until this issue is resolved, all experiments should be halted and the government should not advance any more funding toward this research until the question of when life begins has been determined. Taxpayers do not want taxes to fund any research that is unnecessary and does not improve the quality of life for the rest of society. Pro-life advocates state the moral cost of continuing such research outweighs any impending benefits.

Scientists have stated that the possibilities are both awe-inspiring and bewildering. No one denies the moral dilemma of the embryonic stem cell debate. But to turn back now, researchers say, would be tantamount to turning our backs on a bright, sustaining light because we are terrified of the shadows it creates. No matter where your stance may be, the pros and cons on embryonic stem cell research are persuasive. The research is profound and controversial. In choosing one’s position on this topic, deep research and consideration must be determined.

Science is a creature that continues to evolve at an ever-increasing rate. The transformation from tree shrew, to ape, to human far exceeds the time for the transformation time from an analytical machine, to a calculator, to a computer. However, science, in the past, has always remained distant. Science has allowed advances in production, transportation, and even entertainment; but never in history will science have an affect on our lives, as genetic engineering will undoubtedly do. For the last decade, science has made vast improvements in genetics, monitored by the Human Genome Project.

The goal of this organization is to identify and understand the entire genetic constitution. “They have the daunting task of identifying and mapping all of the eighty thousand genes, in human DNA, they are making new discoveries weekly” (Reuterlinkextra). With these discoveries comes many implications, In reviewing the literature genetic engineering needs to be banned because of the social, religious, ethical, and legal implications. The first step to understanding genetic engineering is to know the start of its creation.

Genetics achieved its first foothold on the secrets of nature’s evolutionary process, when an Austrian Monk named Gregor Mendel developed the basics of how genetics work. Using this, scientist studied the characteristics of organisms for the next one hundred years following Mendel’s discoveries. These early studies concluded that each organism has two sets of character determinants, genes (Stableford 16). For instance, in regards to eye color, a child could receive one set of genes from his or her father that were encoded one blue, the other brown.

The same child could also receive from its mother two brown genes. The conclusion is that the child would have a three out of four chance of having brown eyes and a one out if four chance of having blue eyes (Stableford 16). Inside every person is Deoxyribonucleic acid or more commonly known as DNA. DNA exist as two long, fine strands of DNA spiraling into the famous figure of the double helix. The discovery of DNA is attributed to three scientist, Francis Crik, Maurice Wilkins, and James Dewey.

All were given the Nobel Prize in physiology and medicine in 1962 (Lewin 1). Each strand of DNA is composed of millions of the essential chemical building blocks of life, chemical bases. “There are four bases Adenine (A), Thiamin (T), Guanine (G), and Cytosine (C). These bases can only be paired in certain order, (A) only with (T), (G) only with (C), and vice versa” (Barnes 180). The order of in which these bases occur determine the information available, much as specific letters combine to form words in a sentence.

DNA resides in the nucleus of all of our cells, except the red blood cells. In each nucleus, there are forty-six molecules of coiled, double stranded DNA. Each one of these molecules is housed in a structure called a chromosome. Inside each chromosome are genes. Genes are the chemical message of heredity. “Genes constitute a blueprint of our possibilities and limitations, the legacy of generations of our ancestors, our genes carry the key to our similarities and uniqueness” (Genetic). Genes are made up of the chemical bases Adenine, Thiamin, Guanine, and Cytosine.

These base in a certain order makes up codes, these codes determine if you are short, tall, fat, skinny, and etc. The sex cells are half of the forty-six chromosomes, twenty-three to be exact. In these cells, by random only certain genes are carried by the cells. When the sex cell from a man, sperm, and a sex cell from a woman, an egg, combine their genetic information and a new life is created with the traits from its parents. Genetic engineering is isolating and removing a desired gene from a strand of DNA. In genetic engineering, many different apparatuses are used in removing the gene.

One way DNA can be broken up is by ultra-high frequency sound waves, but this procedure is highly inaccurate way of isolating a desirable trait (Stableford 26). A more accurate way of obtaining the desired trait is the use of restriction enzymes. These enzymes chemically cut the DNA at a particular location on the strand. Now that the trait is cut out, it can be joined to another strand of DNA by using ligases, another enzyme that acts like glue, binding the two pieces together. The final step is making the DNA self replicating by placing it in a cell (Clarke 1).

Does the Human Genome Project effect the moral standards of society? Can the information produced by it become a beneficial asset or a moral evil? For example, X chromosome markers can be used to identify ethnicity. A seemingly harmless collection of information from the Human Genome Project. But let’s assume this information is used to explore ways to deny entry into countries, determine social class, or who gets preferential treatment. Whether or not this type of treatment is acceptable to a moral society remains to be seen.

The major events of genetic history are important to understanding the Human Genome Project. Genetics is the study of the patterns of inheritance of specific traits. The basic beginnings of genetic history lay in the ancient techniques of selective breeding to yield special characteristics in later generations. This was and still is a form of genetic manipulation by “employing appropriate selection for physical and behavioral traits”(Gert, 93). Gregor Mendel, an Austrian monk, completed experiments on garden peas so as to establish the quantitative discipline of genetics.

Mendel’s work explained that the inheritance of traits can be stated by factors passed from one generation to the next; a gene. The complete set of genes for an organism is called it’s genome. A genome creates traits that can be explained due to the inheritance of single or multiple genes affected by factors in the environment. Mendel also correctly stated that two copies of every factor exists and that one factor of inheritance could be dominate over another. The next major events of genetic history involved the discovery DNA (deoxyribonucleic acid).

DNA is a double helix of amino acids and proteins that are encode the blueprint for all living things. DNA was found to be packed into chromosomes, of which 23 pairs existed in each cell of the human body. DNA was also found to be made of nucleotide chains consisting of four amino acid bases known as Adenine, Cytosine, Thymine, and Guanine (A, C, T, and G). Any ordered pair of bases makes a sequence. Sequences are the instructions that produce molecules and proteins for cellular structure and biochemical functions.

A marker is any location on a chromosome where inheritance can be identified and tracked. Markers can be expressed areas of genes (DNA) or some segment of DNA with no known coding function but an inheritance can still be traced. It is these markers that are used to do genetic mapping. By the use of genetic mapping, isolated areas of DNA are used to find if a person has a specific trait, inherent factor, or any other numerous genetic qualities. “Research and technology efforts aimed at mapping and sequencing large portions or entire genomes are called Genome projects”(Congress, 202).

Genome projects are not the effort of a single organization, but instead are groups of organizations working in government and private industry throughout the world. The controversies surrounding the Human Genome Project can be better explained by explaining the structural and moral aspects of the project. Begun in 1990, the US Human Genome Project is a 15-year effort coordinated by the US Department of Energy and the National Institutes of Health.

It’s purposes are to identify all the estimated 80,000 genes in human DNA, determine the sequences of the 3 billion chemical bases that make up human DNA, store this information in databases, and develop tools for data analysis. The objectives of the Human Genome Project are carried out by organizations such as the National Institutes of Health, Howard Hughes Medical Institute, and various other private organizations. These organizations all have two shared objectives, placing “new methods and instruments into the tool-kit of molecular biology” and “building research infrastructure for genetics”(Murphy, 17).

Any attempt to resolve moral issues involving new information from the Human Genome Project requires direct, clear, and total understanding of common morality. Webster’s Dictionary defines morality as ethics, upright conduct, conduct or attitude judged from the moral standpoint. It also defines a moral as concerned with right and wrong and the distinctions between them. A moral theory is the attempt to explain, justify, and make visible “the moral system that people use in making their moral judgments and how to act when confronting a moral problem” (Lee, 34) This theory is based on rational decisions.

With this in mind, the moral system must be known by everyone who is judged by it. This leads to the rational statement that “morality must be a public system” (Lee, 34) The individuals of the public system must know what morality requires of them, and the judgments and guidelines made must be rational to them. Just like any game, the players play by a set of rules and these rules dictate how the game is played. When rules are broken penalties are enforced by the other players, according to the rules.

However, if everyone agrees to change the rules then the game continues without any penalties. Therefore, “the goal of common morality is to lessen the amount of harm suffered by those protected by it” (Lee, 35) and it is constrained by the knowledge and need to be understood by all it applies to. Justified violations also exist in common morality. Just like in the game, a change in the rules causes acceptance. Morality in every instance can be viewed not as an evil by the public perception but as a decision backed by common morals.

Based on the pattern of common morality, the issues of genetic race and class distinction or any other controversies involving the Human Genome Project can be put to a set of common moral standards. Just like the moral standard that says killing is wrong but justifiable in self-defense, the Human Genome Project can be argued along the same line of moral discussion. The justifiable violations that genetic information is based on, depends on the common morality of the public system which, in turn, is based on the common beliefs and distinctions between right and wrong.

Thus the moral dilemma of genetics is simple; will it be an asset or an evil to the individuals public perception of common morality based on the right and wrong of the information? This answer is based on the societies structure. Our particular social structure is largely based on modern medicine. From this it is reasonable to assume that the Human Genome Project is largely accepted by the general populous. So it may be accepted, but is this acceptance propitious? Isn’t there a point where the morality of mapping a persons entire physical and mental character becomes a violator of the personal privacy we all reserve the right to?

That is exactly what the ELSI branch of the Human Genome Project is all about. The US Department of Energy (DOE) and the National Institutes of Health (NIH) have devoted 3% to 5% of their annual Human Genome Program budgets toward studying the ethical, legal, and social issues (ELSI) surrounding availability of genetic information (Murphy, 4) This represents the world’s biggest bio-ethics program, which has become a model for ELSI programs around the world. ELSI was established to develop not only answers but also raise questions about the Human Genome Project.

ELSI’s primary goal is to make clear and informative statements to the public about moral issues surrounding the Human Genome Project. They readily make this information available through publications and their world wide web site. I would now submit to you a list of just a few of the many controversial statements that ELSI is beginning to investigate. 1) Fairness in the use of genetic information by insurers; Employers, courts, schools, adoption agencies, and the military, among others. 2) Who should have access and how will it be used?

Privacy and confidentiality of genetic information 3) Who owns and controls it? Psychological impact and stigmatization due to an individual’s genetic differences How does the information affect an individual, and society’s perceptions of that individual? 4) Genetic testing of an individual for a specific condition due to family history (prenatal, carrier, and presymptomatic testing) and population screening (newborn, premarital, and occupational) Should testing be performed when no treatment is available? Shouldparents have the right to have their minor children tested for adult-onset diseases?

Are genetic tests reliable and interpretable by the medical community? 5) Reproductive issues including informed consent for procedures, use of genetic information in decision making, and reproductive rights. 6) Clinical issues including education of health service providers, patients, and the general public; and implementation of standards and quality control measures in testing procedures 7) Commercialization of products: issues include property rights (patents, copyrights, and trade secrets) and accessibility of data and materials. ) Conceptual and philosophical implications regarding human responsibility, free will versus genetic determinism, and concepts of disease and health. The Human Genome Project in itself is an extremely productive endeavor. While it’s focus is on creating an entire map of the human Genome, it is constantly publishing the steadily increasing volumes of information that are produced every year.

So we return to the question of whether or not the Human Genome Project is an imminent breach of good conscience and morals. There is no doubt that the project can be seen from both sides of the fence. While the data could be manipulated for the wrong purposes, it could also help to accomplish seemingly impossible medical miracles. And so, no doubt, we will fall as a nation into division. However, you are left to decide for yourself, what side of the fence you will be on.

Sometime during our lives, we’ve questioned ourselves at one point just how long has the earth existed and how did life begin? Our Biology book written by: Solomon, Berg, and Martin, shows theories that has taught us that earth is approximately 4. 6 billion years old, and the earliest pieces of life form found was dated back to approximately 3. 8 billion years old. This only leaves a time space of 800 million years between the formation of earth and the creation of life. Since then, new theories have shown that life may have originated earlier then they thought.

From Bernstein, Sanford, and Allamandolas’ article, “Life’s Far-Flung Raw Materials” comes the theory that only about 100 million years after the earliest possible point for earth to support life, evidence shows that organisms were already flourishing. But with the amount of time between this, it almost seems impossible, but not if something were to help the process like space compounds. Christopher Chyba has the leading idea that these space particles did in fact bring in the planet’s water and atmospheric gases.

These space organisms are thought to be responsible for making our earth habitable by bringing in water and gas molecules which would provide our atmosphere and oceans. Also, that the space debris was needed to build life and could have even started the first cellular processes. These space molecules could have absorbed UV-rays from the sun, helping out the weaker molecules, and converting the light energy made into chemical food, which is essential for photosynthesis. Miller showed that the planets first single celled organisms came from a process of chemical steps which is possible for the building blocks of life.

It is stated that everyday, tons of space dust falls to the earth’s surface, some found containing 50% organic carbon, bringing in about 30 tons of organic material. So not only do some scientists argue about space particles bringing in water and gases, but they could also bring in “ready-made-organic molecules such as the ones seen today. From the meteorites that hit the earth they were able to find a variety of 70 amino acids, but only 8 are used by living cells to build proteins. These meteorites also show such compounds including: nucleobases, ketones, quinones, carboxylic acids, amines, and amides.

Astronomers have seen a variety of these organic compounds in the universe and more abundantly in clouds. An experiment was done in a laboratory by Allamandola, where he developed a cloud containing such compounds seen in meteorites. This provided more evidence towards the theory of the earlier development of earth. With the presence of such extraterrestrial compounds like amino acids, quinones, amphiphilic molecules, and other organics, could have very well made it possible for the development or helping towards the development of such life processes.

In conclusion, it is easier for us to believe that extraterrestrial compounds were present during the time of this evolution and that it inhibited the creation of such living organisms. But since this concept is relatively new there is not enough evidence to determine if such compounds had anything to do with the development. Why couldn’t one say that the scientists misinterpreted the development of earth and living organisms all together? This assumption could regenerate all new findings as to when and how the earth began.

Plants evolved more than 430 million years ago from multicellular green algae. By 300 million years ago, trees had evolved and formed forests, within which the diversification of vertebrates, insects, and fungi occurred. Roughly 266,000 species of plants are now living. The two major groups of plants are the bryophytes and the vascular plants; the latter group consists of nine divisions that have living members. Bryophytes and ferns require free water so that sperm can swim between the male and female sex organs; most other plants do not.

Vascular plants have elaborate ater- and food conducting strands of cells, cuticles, and stomata; many of these plants are much larger that any bryophyte. Seeds evolved between the vascular plants and provided a means to protect young individuals. Flowers, which are the most obvious characteristic of angiosperms, guide the activities of insects and other pollinators so that pollen is dispersed rapidly and precisely from one flower to another of The same species, thus promoting out crossing. Many angiosperms display other modes of pollination, including self-pollination.

Evolutionary Origins Plants derived from an aquatic ancestor, but the evolution of their onducting tissues, cuticle, stomata, and seeds has made them progressively less dependent on water. The oldest plant fossils date from the Silurian Period, some 430 million years ago. The common ancestor of plants was a green alga. The similarity of the members of these two groups can be demonstrated by their photosynthetic pigments (chlorophyll a and b,) carotenoids); chief storage product (starch); cellulose- rich cell walls (in some green algae only); and cell division by means of a cell plate (in certain green algae only).

Major Groups As mentioned earlier, The two major groups of plants are The bryophytes- mosses, liverworts, and hornworts–and The vascular plants, which make up nine other divisions. Vascular plants have two kinds of well-defined conducting strands: xylem, which is specialized to conduct water and dissolved minerals, and phloem, which is specialized to conduct The food molecules The plants manufacture. Gametophytes and Sporophytes All plants have an alternation of generations, in which haploid gametophytes alternate with diploid sporophytes.

The spores that sporophytes form as a result of meiosis grow into gametophytes, which produce gametes–sperm and eggs–as a result of mitosis. The gametophytes of bryophytes are nutritionally independent and remain green. The sporophytes of bryophytes are usually nutritionally dependent on The gametophytes and mostly are brown or straw-colored at maturity. In ferns, sporophytes and gametophytes usually are nutritionally independent; both are green. Among The gymnosperms and angiosperms, The gametophytes are nutritionally dependent on the sporophytes.

In all seed plants–gymnosperms and angiosperms–and in certain lycopods and a few ferns, the gametophytes are either female (megagametophytes) or male (microgametophytes). Megagametophytes produce only eggs; microgametophytes roduce only sperm. These are produced, respectively, from megaspores, which are formed as a result of meiosis within megasporangia, and microspores, which are formed in a similar fashion within microsporangia. In gymnosperms, the ovules are exposed directly to pollen at the time of pollination; in angiosperms, the ovules are enclosed within a carpel, and a pollen tube grows through the carpel to the ovule.

The nutritive tissue in gymnosperm seeds is derived from the expanded, food-rich gametophyte. In angiosperm seeds, the nutritive tissue, endosperm, is unique and is formed from a cell that results from the fusion of the polar uclei of the embryo sac with a sperm cell. The pollen of gymnosperms is usually blown about by the wind; although some angiosperms are also wind-pollinated, in many the pollen is carried from flower to flower by various insects and other animals.

The ripened carpels of angiosperm grow into fruits, structures that are as characteristic of members of the division as flowers are. GYMNOSPERMS AND ANGIOSPERMS Gymnosperms Gymnosperms are non-flowering plants. They also make up four of the five divisions of the living seed plants, with angiosperms being the fifth. In gymnosperms, the ovules are not completely enclosed by the tissues of he sporophytic individual on which they are borne at the time of pollination. Common examples are conifers, cycads, ginkgo, and gnetophytes.

Fertilization of gymnosperms is unique. The cycad sperm, for example, swim by means of their numerous, spirally arranged flagella. Among the seed plants, only the cycads and Ginkgo have motile sperm. The sperm are transported to the vicinity of the egg within a pollen tube, which bursts, releasing them; they then swim to the egg, and fertilize it. Angiosperms The flowering plants dominate every spot on land except for the polar regions, the high mountains, and the driest deserts. Despite their overwhelming success, they are a group of relatively recent origin.

Although they may be about 150 million years old as a group, the oldest definite angiosperm fossils are from about 123 million years ago. Among the features that have contributed to the success of angiosperms are their unique reproductive features, which include the flower and the fruit. Angiosperms are characterized primarily by features of their reproductive system. The unique structure known as the carpel encloses the ovules and matures into the fruit. Since the ovules are enclosed, pollination is indirect. History

The ancestor of angiosperms was a seed-bearing plant that was probably already pollinated by insects to some degree. No living group of plants has the correct combination of characteristics to be this ancestor, but seeds have originated a number of times during the history of the vascular plant. Although angiosperms are probably at least 150 million years old as a group, the oldest definite fossil evidence of this division is pollen from the early Cretaceous Period. By 80 or 90 million years ago, angiosperms were more common worldwide that other plant groups.

They became abundant and diverse as rier habitats became widespread during the last 30 million years or so. Flowers and Fruits Flowers make possible the precise transfer of pollen, and therefore, outcrossing, even when the stationary individual plants are widely separated. Fruits, with their complex adaptations, facilitate the wide dispersal of angiosperms. The flowers are primitive angiosperms had numerous, separate, spirally arranged flower parts, as we know from the correlation of flowers of this kind with primitive pollen, wood, and other features.

Sepals are homologous with leaves, the petals of most angiosperms appear to be homologous with stamens, lthough some appear to have originated from sepals; and stamens and carpels probably are modified branch systems whose spore-producing organs were incorporated into the flower during the course of evolution. Bees are the most frequent and constant visitors of flowers. They often have morphological and physiological adaptations related to their specialization in visiting the flowers of particular plants.

Flowers visited regularly by birds must produce abundant nectar to provide the birds with enough energy so theat they will continue to be attracted to them. The nectar visited plants tends to be well protected by the tructure of the flowers. Fruits, which are characteristic of angiosperms, are extremely diverse. The evolution of structures in particular fruits that have improved their possibilities for dispersal in some special way has produced many examples of parallel evolution. Fruits and seeds are highly diverse in terms of their dispersal, often displaying wings, barbs, or other structures that aid their dispersal.

Means of fruit dispersal are especially important in the colonization of islands or other distant patches of suitable habitat. VASCULAR PLANT STRUCTURE Vegetative Organs A vascular plant is basically an axis consisting of root and shoot. The root penetrates the soil and absorbs water and various ion, which are crucial for plant nutrition, and it also anchors the plant. The shoot consists of stem and leaves. The stem serves as a framework for the positioning of the leaves, the principal places where photosynthesis takes place.

Plant Tissue The stems and roots of vascular plants differ in structure, but both grow at their apices and consist of the same three kinds of tissues: 1. Vascular tissue–conducts materials within the structure; it consists of two types: (1) xylem–conducts water and dissolved inerals (2) phloem–conducts carbohydrates, mainly sucrose, which the plant uses for food, as well as hormones, amino acids, and other substances necessary for plant growth 2. Ground tissue–performs photosynthesis and stores nutrients; the vascular tissue is embedded 3.

Dermal tissue–the outer protective covering of the plant Growth Plants grow by means of their apical meristems, zones of active cell division at the ends of the roots and the shoots. The apical meristem gives rise to three types of primary meristems, partly differentiated tissues in which ctive cell division continues to take place. These are the protoderm, which gives rise to the epidermis; the procambium, which gives rise to the vascular tissues; and the ground meristem, which becomes the ground tissue. The growth of leaves is determinate, like that of flowers; the growth of stems and roots is indeterminate.

Water reaches the leaves of a plant after entering it through the roots and passing upward via the xylem. Water vapor passes out of the leaves by entering intercellular spaces, evaporating, and moving out through stomata. Stems branch by means of buds that form externally at the point where he leaves join the stem; roots branch by forming centers where pericycle cells begin dividing. Young roots grow out through the cortex, eventually breaking through the surface of the root. Propagation An angiosperm embryo consists of an axis with one or two cotyledons, or seedling leaves.

In the embryo, the epicotyl will become the shoot, and the radicle, a portion of the hypocotyl, will become the root. Food for the developing seedling may be stored in the endosperm at maturity or in the embryo itself. NUTRITION AND TRANSPORT IN PLANTS The body of a plant is basically a tube embedded in the ground and xtending up into the light, where expanded surfaces–the leaves–capture the sun’s energy and participate is gas exchange. The warming of the leaves by sunlight increases evaporation from them, creating a suction that draws water into the plant through the roots and up the plant through the xylem to the leaves.

Transport from the leaves and other photosynthetically active structures to the rest of the plant occurs through the phloem. This transport is driven by osmotic pressure; the phloem actively picks up sugars near the places where they are produced, expanding ATP in the process, and unloads them here they are used. Most of the minerals critical to plant metabolism are accumulated by the roots, which expend ATP in the process. The mineral are subsequently transported in the water stream through the plant and distributed to the areas where they are used–another energy-requiring process.

Soil Soils are produced by the weathering of rocks in the earth’s crust; they vary according to the composition of those rocks. The crust includes about 92 naturally occurring elements. Most elements are combined into inorganic compounds called minerals; most rocks consist of several different minerals. They weather to give rise to soils, which differ according to the composition of their parent rocks. The amount of organic materials in soils affects their fertility and other properties. About half of the total soil volume is occupied by empty space, which my be filled with air or water depending on moisture conditions.

Not all of the water in soil, however, is available to plants, because of the nature of water itself. Water Movement Water flows through plants in a continuous column, driven mainly by transpiration through the stomata. The plant can control water loss primarily by closing its stomata. The cohesion of water molecules and their adhesion to the walls of the very narrow cell columns through which they pass are additional important factors in maintaining the flow of water to the tops of plants. The movement of water, with its dissolved sucrose and other substances, in the phloem does not require energy.

Sucrose is loaded into the phloem near sites of synthesis, or sources, using energy supplied by the companion cells or other nearby parenchyma cells. The sucrose is unloaded in sinks, at the places where it is required. The water potential is lowered where the sucrose is oaded into the sieve tube and raised where it is unloaded. Nutrient Movement Apparently most of the movement of ions into a plant takes place through the protoplast of the cells rather than between their walls. Ion passage through cell membranes seems to be active and carrier mediated, although the details are not well understood.

The initial movement of nutrients into the roots is an active process that requires energy and that, as a result, specific ions can be can be maintained within the plant at very different concentrations from the soil. When roots are deprived of oxygen, they lose their ability to absorb ions, a efinite indication that they require energy for this process to occur successfully. A starving plant–one from which light has been excluded–will eventually exhaust its nutrient supply and be unable to replace it.

Once the ions reach the xylem, they are distributed rapidly throughout the plant, eventually reaching all metabolical active parts. Ultimately the ions are removed from eh roots and relocated to other parts of the plant, their passage taking place in the xylem, where phosphorus, potassium, nitrogen, and sometimes iron may be abundant in certain seasons. The accumulation of ions by lants is an active process that usually takes place against a concentrations gradient and requires the expenditure of energy.

Carbohydrates Movement Carbohydrate movement is where water moves through the phloem as a result of decreased water potential in areas of active photosynthesis, where sucrose is actively being loaded into the sieve tubes, and increased water potential in those areas where sucrose is being unloaded. Energy for the loading and unloading of the sucrose and other molecules is supplied by companion cells or other parenchyma cells. However, the movement of water and issolved nutrients within the sieve tubes is a passive process that does not require the expenditure of energy. Plant Nutrients Plants require a number of inorganic nutrients.

Some of these are macronutrients, which the plants need in relatively large amounts, and others are micronutrients, those required in trace amounts. There are nine macronutrients: 1. Carbon 2. Hydrogen 3. Oxygen 4. Nitrogen 5. Potassium 6. Calcium 7. Phosphorus 8. Magnesium 9. Sulfur that approach or exceed 1% of a plant’s dry weight, whereas there are seven micronutrients: 1. Iron 2. Chlorine 3. Copper 4. Manganese 5. Zinc 6. Molybdenum 7. Boron that are present only in trace amounts. PLANT DEVELOPMENT Differentiation in Plant Plants, unlike animals, are always undergoing development.

Their cells do not move in relation to one another during the course of development, which is a continuous process. Animals undergo development according to a fixed blueprint that is followed rigidly until they are mature. Plants, in contrast, develop constantly. The course of their development is mediated by hormones, which are produced as a result of interactions with the external environment. Embryonic Development Embryo development in animals involves extensive movements of cells in elation to one another, but the same process in plants consists of an orderly production of cells, rigidly bound by their cellulose-rich cell wall.

The cells do not move in relation to one another in plant development, as they do in animal development. By the time about 40 cells have been produced in an angiosperm embryo, differentiation begins; the meristematic shoot and root apices are evident. Germination in Plants In the germination of seeds, the mobilization of the food reserves stored in the cotyledons and in the endosperm is critical. In the cereal grains, this process is mediated by hormones of the kind known as gibberellins, which ppear to activate transcription of the loci involved in to production of amylase and other hydrolase enzymes.

REGULATION OF PLANT GROWTH Plant Hormones Hormones are chemical substances produced in small quantities in one part of an organism and transported to another part of the organism, where they bring about physiological responses. The tissues in which plant hormones are produced are not specialized particularly for that purpose, nor are there usually clearly defined receptor tissues or organs. The major classes of plant hormones–auxins, cytokinins, gibberellins, thylene, and abscisic acid–interact in complex ways to produce a mature, growing plant.

Unlike the highly specific hormones of animals, plant hormones are not produced in definite organs nor do they have definite target areas. They stimulate or inhibit growth in response to environmental clues such as light, day length, temperature, touch, and gravity and thus allow plants to respond efficiently to environmental demands by growing in specific directions, producing flowers, or displaying other responses appropriate to their survival in a particular habitat. Tropisms Tropisms in plants are growth responses to external stimuli.

A phototropism is a response to light, gravvitropism is a response to gravity, and thigmotropism is a response to touch. Turgor Movement Turgor movements are reversible but important elements in adaptation of plants to their environments. By means of turgor movements, leaves, flowers, and other structures of plants track light and take full advantage of it. Dormancy Dormancy is a necessary part of plant adaptation that allows a plant to bypass unfavorable seasons, such as winter, when the water my be frozen, or periods of drought. Dormancy also allows plants to survive in many areas where they would be unable to grow otherwise.