Biochemistry - Effect of Temp. on Catalase Activity

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Chemistry of Life Practical Investigation | Investigation of a Factor Affecting Enzyme Action|
By: Jerry Li
HL Biology
Term 1 Year 11
HL Biology


1 Design2
1.1 Defining the problem2
Research Question2
Background Information2
Investigation Variables3
1.2 Controlling Variables4
Control Variables4
Uncontrolled Variables4
Control Experiment4
1.3 Experimental Method5
Materials and Equipment5
Practical Safety and Risk Assessment6
Setup Diagram6
2 Data collection and processing7
2.1 Recording Raw Data7
Sufficiency of Data7
Results – Raw Data7
Qualitative Observations:8
2.2 Processing Data9
Statistical Processing - Calculations9
2.3 Presenting Processed Data10
Results Table10
3 Conclusion and Evaluation11
3.1 Conclusion11
Conclusion Statement11
Conclusion Explanation11
3.2 Evaluation Procedures:11
Errors/Limitations in Experimental procedure11
3.3 Improving the Investigations12
Suggestions for Improvements12

1 Design
1.1 Defining the problem
Research Question
This lab will be driven by the research question; do changes in temperature (from 0˚C, 7˚C, 21˚C, 37˚C, and 90˚C) have an effect on the activity of the enzyme catalase (found in beef liver) in the breakdown of hydrogen peroxide? Hypothesis

If liver is placed in different temperatures of 0˚C, 7˚C, 21˚C, 37˚C, and 90˚C and hydrogen peroxide is added to each piece of liver, then the liver placed in 37˚C will have the largest reaction height. The liver in 90˚C will have the smallest reaction height, followed by the liver in 0˚C, then 7˚C, and then 21˚C.

Background Information
Pearson Baccalaureate: Standard Level Biology Developed Specifically for the IB Diploma defines enzymes as “protein molecules which act as catalysts for reactions. As catalysts, the real function of enzymes is to lower the activation energy of the reactions that they catalyze” (166). Enzymes are proteins; therefore the liver has a particularly high concentration of catalase. When hydrogen peroxide (H2O2) is added to liver, catalase catalyzes a reaction in which the hydrogen peroxide is broken down into oxygen gas (O2) and liquid water (H2O). Hydrogen peroxide is a toxic chemical that is produced as a byproduct of many normal cellular reactions, so it is crucial that catalase in the liver breaks the hydrogen peroxide down into the two harmless substances of oxygen gas and liquid water. The hydrogen peroxide must be quickly degraded or converted, and catalase accomplishes this task because one molecule of catalase can deal with six million molecules of hydrogen peroxide in one minute. Enzymes and the temperature of their environment are particularly important to the human body because “Many of the reactions which represent the digestive process would need far higher temperatures than we are able to maintain safely if enzymes were not involved” (166).

The prediction in the hypothesis is based on the concept of denaturation. As Pearson Baccalaureate: Standard Level Biology Developed Specifically for the IB Diploma states, “Reactions which use enzymes do have an upper limit. That limit is based on the temperature at which the enzyme (as a protein) begins to lose its three-dimensional shape due to intramolecular bonds being stressed and broken. When an enzyme loses it shape, including the shape of the active site, it is said to be denatured” (75). Due to denaturation, the liver placed in 100˚C will have the smallest reaction height because at this temperature catalase will begin to denature. Because “reactions with or without enzymes will increase their reaction rate as temperature (and thus...
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