Lab Two

Lab Two - Period 6 AP Bio J. Michael Lindle 1 Enzyme...

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Period 6 AP Bio J. Michael Lindle 1 Enzyme Catalysis Introduction: In this lab, we used titration to find the rates of enzyme reactions. We put H 2 O 2 in 7 different beakers and added catalase to each of them. Each of the beakers had an as- signed amount of time for the H 2 O 2 to be exposed to the catalase, 10, 30, 60, 90, 120, 180, and 360. When the time ran out we titrated KMnO 4 and recorded how many mL of KMnO 4 it took for the solution to turn purple. This shows us how much H 2 O 2 is left. For example: 4.1 mL of KMnO 4 reacted with the H 2 O 2 for the 10 seconds of exposure, while only 3.4 mL of KMnO 4 reacted with the H 2 O 2 for the 30 seconds of exposure. This trend continues. The time was regulated by adding sulfuric acid after the amount of time de- sired was passed. The sulfuric acid denatures the catalase, making it unusable. The point of finding the baseline is to acknowledge how much H 2 O 2 is present in the original solution so it can be compared to the data shown below (Table 2.1). This is the control so you can compare how much 1.5% H 2 O 2 is present. This allows you to make assump- tions that when the H 2 O 2 is broken down by the catalase less KMnO 4 will be used each time (as the amount of time exposed to the catalase raises). This proves that H2O2 was broken down. Part 2C shows the decomposition of uncatalyzed H 2 O 2 over 24 hours which will be compared to catalyzed H 2 O 2 . The fact that the uncatalyzed H 2 O 2 should not have decomposed as much as the catalyzed H 2 O 2 shows that the catalase is faster at reacting. Also, the rate of enzymes is faster at the beginning of the reaction because more substrate is exposed as opposed towards the end of the reaction. Changing the pH of the environment will denature enzymes, making them unusable, (sulfuric acid rendered the catalase useless).
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Period 6 AP Bio J. Michael Lindle 2 Catalase is found in almost all living organisms that are exposed to oxygen on a regular basis. Catalase’s function is to decompose hydrogen peroxide to form oxygen and water. One molecule of catalase will convert 50,000 hydrogen peroxide molecules to oxygen and water per second. Catalase is composed of four polypeptide chains, called a tetramer. Each of these chains contains over 500 amino acids. In 1811 Louis Jacques Thénard declared that catalase was a substance, but could not put a name on it, he only knew that this substance broke down H
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This note was uploaded on 01/25/2012 for the course BIO 1111 taught by Professor Odolecki during the Fall '10 term at GWU.

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Lab Two - Period 6 AP Bio J. Michael Lindle 1 Enzyme...

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