Name_________________________________________

Web Lab on Enzymes: http://bioweb.wku.edu/courses/Biol114/enzyme/enzyme1.asp

Part I - Measuring the Rate of Reaction
Introduction:
1. Write the equation for the reaction that the enzyme catalase carries out.

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2. Why does raising the temperature increase the rate of the reaction?

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3. What can be used to STOP the reaction of catalase? Why does this work?
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Click on the "more" button.
4. What is the active site? _______________________________________________________
5. If we start with 3 ml of H2O2 from your bathroom cabinet and add catalase. After 3 minutes we measure the amount of H202 remaining and find 1 ml remains.
How much H202 was consumed in the reaction? ____________________
6. If we repeated the experiment above but found 2 ml of H202 remaining,
would this indicate a lower or higher rate of reaction? _________________________________

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7. The Experimental Procedure - fill in the blanks
____________________ tubes containing catalase and _____________________ at different temperatures and examine the rate of enzyme activity by ________________________ any remaining (unreacted) substrate. This will give us an indirect measure of the substrate converted to ___________________ and therefore the _____________________ of reaction.
8. When you added H2O2 to the test tubes you added substrate or enzyme? ______________
9. The four tubes are placed in what temperatures? ___________________________________

10. After you added catalase, wait 3 minutes and then add what? _______________ Why is this step important?
11. What reaction occurred in the test tubes? _______________________________________
12. Titrate using potassium permanganate each of the four tubes and fill out the table below.

13. (Click on "back to the lab") Which tube had the highest rate of reaction? How do you know?
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14. What variable(s) would have caused the differences in reaction rates for each tube? _________________________________________

15. Amylase is an enzyme in saliva that helps to break starches into sugars. An experiment with amylase and starch was set up similar to the one you did above and the following results were obtained. Instead of measuring the amount of starch remaining in the tube, scientists measured the amount of glucose produced.

Which of the tubes in the above experiment was the coldest? ________ The warmest? _______
Explain how you know this. _____________________________________________________
16. Indicators such as potassium permanganate and iodine can be used to measure the amount of substance left in a test tube or beaker. For each of the indicators, list whether they serve to indicate substrate left, or product created
Amylase ____________________ Potassium Permanganate ________________________

Part II - Examining the Factors that Affect the Rate of Reaction

Site: Johnson Explorations (the site URL changes go to Google and type Johnson Explorations to access the site)
Click on "Cell Chemistry: Thermodynamics"
Click on the "skip intro" after the shockwave simulation opens to begin simulation

1. For each of the enzymes you can use in the lab, you will need to plot points and a graph. Use the graphs to determine the optimal temperature and pH of each of the enzymes and fill out the table below.

Questions:
2. In general, when you increase the amount of enzyme, what happens to the reaction rate?

3. What is meant by "optimal temperature" or "optimal pH"?

4. Analyze this graph. What is the graph showing you about the enzyme?