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Lab Report Enzyme Experiment

Hypothesis: If pH is increased or decreased past the enzyme’s optimum pH, the number of products produced by the enzyme will decrease because the enzyme will become denatured.

Variables: The Independent variable is the pH of the environment. The uncertainty of pH is ± 1. pH is a unitless value. The Dependent variable is the number of products produced. The uncertainty of this this measurement is ± 1 product. In order for this experiment to be controlled, many variable were identified and held constant. If these variables were not to be held constant than the findings of this experiment would be meaningless because there would be no way of desiring if the independent variable was the cause of the changes which were recorded In this experiment, there was one enzyme. The uncertainty was ± 1 enzyme.

There were 20 substrains which had an uncertainty of ± 1 . The temperature was 25oC the uncertainty of this measurement was ± 1oC. The volume of the container was 400 mL, this had the uncertainty of ± 1 mL. For each trial, the duration of the simulation was 30 seconds. The uncertainty of this measurement was 0.4 seconds. (Even though a stop watch has an uncertainty of 0.01 seconds, the average human reaction time is 0.2 seconds.

Therefore two separate uncertainties were created from starting and stopping, from which the uncertainty 0.4 seconds was derived) The control group for this experiment will be when the pH is 7, this is a control group because when the pH is seven the environment is considered neutral. This means that the environment is neither acidic or basic. Additionally this is a good control group because the majority of enzymes have an optimum pH of 7. The uncertainty of pH is ± 1 and pH is unitless.

Materials: 1-computer 1-piece of paper 1-pencil 1-stopwatch Internet connection Online Enzym Simulator

Procedure: The computer was turned on and was connected to the internet. An enzyme simmulation was acessed from http://www.kscience.co.uk/animations/model.swf The pH value was set as 7. Each of the control variables was set to it’s default value (one enzyme, 20 substrates, 0 inhibitors, Temperature at 250C and Container size as 400mL) The button on the simulation labeled “set-up” located on the righthand side of the screen was clicked. The experimental set-up appeared. To begin the experiment, the button of the simulation labeled “start” was clicked. (This button was located in the bottom lefthand corner of the screen.) A stopwatch was used to time the simulation for thirty seconds.

Once thirty seconds had elapsed, the button labeled “stop” was clicked in order to pause the simulation. Using the key to identify the products,the number of products that were produced during the simulation were counted. This value was recorded in the data table. The procedure in steps 3-10 was repeated five times, so that data was collected in a total of six trials. The average number of products produced was calculated by adding the sum of the number of products produced in each trial and dividing by the number of total trials. This value was recorded on the far right hand column of the data table. The procedure in steps 4-12, was repeated for each of the other thirteen pH values.

Experimental Set-up

Data: The Effect of pH on the number of products produced

Qualitative Data: When the pH of the environment was 1, an average of 5 products were produced. As this pH value increased to 2, an average of 8 products were produced. The large quantity of products was produced when the pH was equal to four. When the pH value increased to five, the average amount of product which was produced decreased to 9. As the pH values continued to increase, the number of products produced decreased even further. When the pH was equal to 8, zero products were produced. All of the pH values which were higher than 8, yielded the same result; zero products produced.

Statistical Analysis: Calculation 1: Average Number of Products Produced Average = term 1+term 2…+term n n Average = 3+5+5+3+7+7 6 Average = 30 6 Average = 5

Conclusion and Evaluation: When the pH is increased or decreased past the enzyme’s optimum pH, the number of products produced by the enzyme will decrease. The enzyme produced the largest number of products when the pH was four. When the environment became more basic, the enzyme produced fewer products. Only nine products were produced when the pH of the environment was 5.

Furthermore, with a pH of seven, even fewer products were produced. For all pH values which were greater than seven, zero products were produced. Additionally as the pH of the environment decreased to values less than four, fewer and fewer products were produced. When the pH was three, only nine products were produced and when the pH was one only five products were produced. All of the data was not reliable because there was an extremely wide range of data which was collected. When the pH of five was tested, the maximum amount of products produced was thirteen while the lowest value was five.

Furthermore, the control variable were the pH was neutral signifies that the acidity or basicity of an enzyme’s environment impacts its productivity. Even though the enzyme did not have its optimum pH at seven, this signifies that the enzyme likely functions in an acidic environment, because the optimum pH for the enzyme was four. An enzyme is a protein whose structure is dependent on hydrogen bonding, when these hydrogen bonds are interfered with, the structure of the enzyme will change. An enzyme’s structure is essential to its function in the process of producing product. When the structure of an enzyme is altered it is said to be denatured.

Once an enzyme is denatured it is no longer able to function. This explains why zero products were produced once the pH was greater than seven. One weakness of this data is that there is a huge variety of variance between the number of products which were produced at the same pH level. This limitation is fairly significant because the low quality of precision causes the accuracy to be questioned. Additionally, because the simulation only included values to the nearest whole digit, the true optimum pH could not be found because in all likelihood the optimum pH would occur between whole digit values.

One way to strengthen the data would be to conduct more trials. If the large variance is the result of random errors, than averaging many trials together would reduce the error in this measurement. If the errors in the data were the result of systematic errors in the procedure than more trials would not reduce the amount of error. In a systematic error, all of the recorded data is higher or lower than the actual value. Because there is a wide range of data values in this experiment, it signifies that this variance is likely the result of random error.

As more data was collected in the lab, the average amount of products produced began to follow a stronger trend, therefore, if there were even more trials, the data itself would be stronger. Another improvement to this experiment would be to increase the time of each trial to one minute. Having longer trials might cause there to be more consistent measurements of the number of products produced. Even though the results of this experiment were not very precise, I believe them to be accurate because the results of this experiment follow the results of other experiments which were researched. The results of this experiment are reproducible because using an online simulation eliminates many sources of error that each distinct tester might face in different locations.

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