1. CAPT Lab: Investigating the Effect of Temperature on Enzyme Activity Created by Mr. Cross - 2007

2. Purpose This presentation serves to either serve as a reminder to those students that participated in this CAPT inquiry lab or to introduce this lab to those students that did not participate in activity.

3. Directions Read through the presentation and answer the questions as they are proposed.

4. Background Enzymes are proteins that act as catalysts which speed up chemical reactions. They do this by lowering the energy needed for a reaction to occur, the activation energy. Reaction pathway without enzyme Activation energy without enzyme Reaction pathway with enzyme Reactants Products Activation energy with enzyme

5. Effects of Temperature and pH When the temperature or pH of the enyzme environment is not ideal the reaction may slow down or not occur at all.

6. Problem Statement How does temperature affect the rate of an enzyme catalyzed reaction?

7. Materials Raw liverPetri dish Dropper pipette1 % Hydrogen Peroxide Solution Liver Puree25 mL graduated cylinder 50 mL BeakersFilter-paper disks Glass marking pencilIce bath 3 thermometersWarm water bath Clock or stop watchForceps Hot plate

8. Part A: Observing the Catalase Reaction 1.Using the pipette place a few drops of hydrogen peroxide on the liver. Liver contains catalase which breaks down hydrogen peroxide into oxygen gas (bubbles) and water. 2H 2 O 2 (aq)  2H 2 O (l) + O 2 (g)

9. Measuring Catalase Activity Use a graduated cylinder to place 25 mL of Hydrogen peroxide solution in a 50mL beaker. Dip the filter paper disk into the puree. Place the filter paper disk on a paper towel for 4 seconds to remove any excess liquid. Place the filter paper disk at the bottom of the hydrogen peroxide solution. Record the number of seconds it takes the filter paper to float to the top of the hydrogen peroxide solution.

10. Your Task Design an experiment to test the affects of temperature on enzyme activity. Write a Hypothesis

11. Sample Hypothesis: As the temperature of an enzyme’s environment increases the rate of the catalase reaction will decrease.

12. What is the independent variable (manipulated variable)? Temperature What is the dependent variable (responding variable)? Rate of the reaction

13. Design an Experiment 1.Create 5 different water bath environments by using the ice and hot plates. a. cold water – 2 degrees C b. room temperature water – 18 degrees C c. luke warm water – 30 degrees C d. warm – 47 degrees C e. hot water – 64 degrees C

14. 2.Using the graduated cylinder pour 25 mL of the Hydrogen peroxide into each of the 50 mL beakers. 3.Label each beaker so they correspond with step 1. 4.Place each beaker into their proper water bath for 10 minutes. 5.Measure the temperature of the hydrogen peroxide solution and record.

15. 6.Dip the filter paper disk into the liver puree for 5 seconds. 7.Remove the disk and place it on the paper towel to remove the excess liquid. 8.Immediately place the disk at the bottom of the hydrogen peroxide solution. 9.Record how long it takes for the disk to float. 10.Repeat steps 5-9 for each solution.

16. The following data was recorded by the student Water Environment Temperature (Celsius) Seconds to Float Cold235 seconds Room Temperature 1815 seconds Luke warm265 seconds Warm403 seconds Hot49Did not Float

17. Note: 49 degrees Celsius never floated. Student 1’s Graph

18. Student 2’s Graph

19. State which graph is better and provide reasons. Graph 2 has the independent variable (temperature) on the y axis when it should be on the x axis. Graph 2 should define the temperature scale as Celsius. Graph 1 informs the reader that the filter paper did not float at 49 degrees Celsius. Note: 49 degrees Celsius never floated.

20. What conclusions can be drawn from Student 1’s Data? As the temperature of the catalase increases the time for the disk to rise decreases. The peak temperature range for catalase activity is between 25 – 40 degrees Celsius. Somewhere between 40 and 49 degrees Celsius the enzyme stops working. Note: 49 degrees Celsius never floated.

21. What could be done to improve the validity of the experiment? Increase the number of trials at each temperature.

22. What further investigations could be done? Investigate the affects of temperature at the 30 - 60 degree Celsius range.

23. Making Connections Many mammals have body temperatures close to 37 degrees Celsius. Does the graph indicate that catalase is most active when it is close to the temperature at which it exists in a mammal? Yes it does. The graph clearly shows that the enzyme activity is at its greatest between 30 – 40 degrees Celsius.