The Effect of Temperature on the Enzyme Catalase

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The Effect of Temperature on the Enzyme Catalase
Stephen Francis
Biology 183
This experiment was performed to determine the resultant effect of temperature change on the reaction between the enzyme catalase and hydrogen peroxide. This experiment was performed by measuring and comparing the amount of oxygen bubbles produced and the absorbance of the catalase and hydrogen peroxide solution over time at room temperature, 2°C, 50°C, and 60°C. The overall result of this experiment proved that this reaction works best at room temperature, slows down when the temperature is lowered, and does not take place when the temperature gets too high due to the enzyme denaturing at these higher temperatures. The hypothesis that was expected for this experiment was supported by the actual experiment for the most part, but due to an error in the absorbance measurement, the results were somewhat skewed leaving part of the hypothesis unproved for this part of the experiment. Overall it was concluded that by varying the temperature too much, the reaction speed was heavily affected even to the point where it didn’t happen at all when the enzyme was heated too much. Introduction

This experiment tested the effects of temperature on the reaction between catalase and hydrogen peroxide. Enzymes are catalysts that increase the rate of chemical reactions by reducing the activation energy needed for the reaction to take place (Hayden McNeill 2013). Catalase is an enzyme that is found in animal, plant, fungi, and bacteria cells, and plays a role in breaking down hydrogen peroxide into water and oxygen (Hayden McNeill 2013). Hydrogen peroxide can be toxic to cells at high concentration, so this is an important reaction for cells to undergo. To measure the effect of temperature change, oxygen bubble levels and absorbance levels were measured over time as the reaction took place (or didn’t take place in some circumstances). In order to measure the results at both ends of the spectrum, results of a heated catalase and a cooled catalase were measured as well as at room temperature. The independent variable was the change in temperature and the dependent variable was the absorbance levels and oxygen bubble levels measured in the experiment.

The hypothesis for this experiment was that by raising a temperature too much, the reaction wouldn’t take place and that by cooling it the reaction speed would be much slower than at room temperature. This is because at high temperatures enzymes tend to become denatured, which causes it to lose the properties that make it able to break down the hydrogen peroxide. Also most enzymes work best at a temperature around room temperature, so cooling it would slow down the reaction until it returned to a temperature near room temperature. Methods

Procedure A: Oxygen Bubble Levels
The first part of this experiment was a qualitative measurement of the activity of enzymes when mixed with 3% H2O2. First four test tubes were labeled with the numbers 1 – 4. For tube number one, 1mL of deionized water was mixed with 5mL of 3% H2O2. This was the control variable for the first part of the experiment. The second test tube contained a ¼” X ¼” potato cube mixed with 5mL of 3% H2O2. The third test tube contained 1mL of the enzyme catalase mixed with 5mL of 3% H2O2. The fourth test tube contained the enzyme catalase which had been boiled for 5 minutes, then cooled for 2 minutes and mixed with 5mL of 3% H2O2. The results were measured qualitatively, and compared to one another to determine which mixture produced the most oxygen bubbles.

Next the effects of temperature change were tested on the enzyme catalase’s reaction with the hydrogen peroxide. First two test tubes were labeled “Enz A” and “Enz B” and 1mL of catalase was pipetted into each. Then two other test tubes were labeled “A Sub” and “B Sub” and 5mL of 3% H2O2 was pipetted into each of these. The test tubes labeled “Enz A” and “A Sub” were placed in an ice...
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