The Role of Enzymes

Rucker, Jessie B. Curie Metro High School

Objectives: To explore the role of enzymes in chemical reactions. To determine what kinds of cells contain more catalase than others. Apparatus and Materials: Chalk Manganese dioxide Potato Boiling water Raw hamburger Graduated cylinder Raw liver scalpel Boiled liver 10-mL test tube Spinach leaf Test tube rack Carrot Spot plates 3 percent hydrogen peroxide Recommended Strategy: Phenomenological approach Comparisons, analogies, and summarization 1. Review the following terms: organic compounds, dehydration synthesis, hydrolysis, potential energy, kinetic energy, and activation energy. 2. Place two keys on an overhead projector and have the students compare them to the structure of enzymes. 3. Using paper models on the overhead projector, demonstrate to the students the role of enzymes in hydrolysis and dehydration synthesis. STUDENTS ARE NOW READY TO BEGIN THE EXPERIMENT. PART I Measure 2 mL of hydrogen peroxide,H2O2, in a graduated cylinder
and pour it into a test tube. Add to the test tube enough manganese
dioxide, MnO2, to cover the end of a scalpel.

1. Describe the reaction.
2. When the reaction ends, add 2 mL more hydrogen peroxide to the
test tube. Does the reaction occur again?
3. When the reaction ends, add a little more manganese dioxide.
Does the reaction occur again?
4. Based on your observations, which of the following statements
is the most probable assumption? Circle the letter of the
statement you choose.
a. The hydrogen peroxide is used up and the manganese dioxide
remains unchanged.
b. The manganese dioxide is used up and the hydrogen peroxide
remains unchanged.
c. Both the hydrogen peroxide and the manganese dioxide are
used up.
d. Neither the hydrogen peroxide nor the manganese dioxide is
used up.

Place three small pieces of each: chalk, hamburger, liver, spinach,
potato, and carrot on a spot plate. Pour enough hydrogen peroxide
on each food stuff to fill the depression. Be sure to prepare the
same amount of each food stuff and to keep them separate.

Note the speeds of the reactions. The faster the reaction, the
more vigorously the liquid bubbles and the warmer the container
becomes. Make a data chart, list the items in order from the
fastest reacting to the slowest reacting.

5. Which substances contain more of the enzyme, those at the top
of the list or those at the bottom?
6. Are the meats near the top or bottom of the list? the plants?
7. Which, if any, of the items did not produce a reaction? If a
substance produced no reaction, explain why.

Place three small pieces of raw liver and three small pieces of
boiled liver on your spot plate. Fill each depression with
hydrogen peroxide.

8. Describe what happens.
9. Based on this test, what assumption can you make about the
effect of boiling enzymes?

10. What two products does hydrogen peroxide change into when it
breaks down?
11. What effect does a catalyst have on this chemical reaction?
12. What do you think causes the bubbling in this reaction?
13. What is the function of an enzyme?
14. What enzyme acts on hydrogen peroxide in living organisms?
15. Would this enzyme act on chemicals other than hydrogen
peroxide? Why or why not?

1. Summarize what you have learned about the role of enzymes.
2. What analogy can be best used to describe the role of
3. Write a list of terms that were used to help you to under-
stand how enzymes operate. Use each term in an appropriate
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