The Role of Enzymes
Return to Biology Index
Rucker, Jessie B. Curie Metro High School
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
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
STUDENTS ARE NOW READY TO BEGIN THE EXPERIMENT.
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
b. The manganese dioxide is used up and the hydrogen peroxide
c. Both the hydrogen peroxide and the manganese dioxide are
d. Neither the hydrogen peroxide nor the manganese dioxide is
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
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
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