Teacher
Enzyme Catalyst Lab
NGSSS:
SC.A.912.L.18.1 Describe the basic molecular structures and primary functions of the four
major categories of biological macromolecules.
(Also addresses SC.912.L.18.11)
Purpose of Lab:
 Investigate the effect of variations in enzyme concentration on rate of reaction.
 Investigate the effect of variations in substrate concentration on rate of reaction.
Prerequisites: Review with students how enzymes affect activation energy. Describe how an
enzyme’s shape is important to its function. Ensure that students know the difference between
the meaning of the word catalase and the word catalyst. Some students may confuse these
terms. It is important that students are familiar with all of the vocabulary terms listed in the
student section.
Materials (per group):
 Yeast solution
 Eight 50 ml beakers
 Hydrogen peroxide
 Distilled water
 Filter paper disks




Marking pencil
Forceps
Paper towels
Graph paper
Procedure: Day of Activity:
What the teacher will do:
a. Prep work: Obtain all materials and prepare yeast solution well before
beginning this lab activity.
b. Before passing out the lab, have the students think about what processes in
the body use enzymes to function. Be sure to discuss as a class the vital
enzymes for human digestion such as protease, amylase, lipase, etc.
c. Use the following questions to engage student thinking during a pre-lab
discussion:
1. What does catalyzed mean?
2. How does the induced-fit model apply to this lab activity?
3. What other factors can affect the rate of reaction?
Before
4. What is meant by “denaturation of the protein?”
activity:
d. Assign four students per group. For student reference, make copies of the
“Lab Roles and Their Descriptions.”
e. Review the background information with the students.
1.
Write the formula for hydrogen peroxide, H2O2, on the white board.
Then write the following equation for its decomposition: 2H2O2  2H2O
+ O2
2.
Ask the following question. If hydrogen peroxide is a liquid, what
might you expect to see when it decomposes? (Accept all reasonable
answers.) Bubbles of gas will be visible as oxygen is released and water
remains.
3. Explain to students that the function of the enzyme, catalase, is to
Teacher
During
activity:
After
activity:
speed up the decomposition of hydrogen peroxide.
f. Read aloud or have a student read aloud the problem statement at the
beginning of the investigation. Based upon the problem statement, have
students decide on an individual hypothesis for their lab group, focusing on
lower concentration effects and higher concentration effects on the rate of
reaction.
g. Remind students that they will complete a minimum of three trials for each
peroxide solution.
What the teacher will do:
a. Circulate throughout the room and help any group that is having trouble
with any aspect of the procedure.
b. Monitor students for safety procedures, and keep students focused on their
hypothesis.
c. The following questions may be used to engage student thinking during the
lab activity:
1. What is the substrate in this investigation? What is the enzyme?
2. What is the function of the enzyme in this investigation? 3. What are the
reactants and products in the following equation? 2 H2O2 → 2 H2O + O2
What the teacher will do:
a. Ask the following questions.
1. Was your hypothesis confirmed or refuted?
2. How do your results compare to your preconceptions of what would
happen?
3. What experimental conclusions can you now draw from your data?
b. Ask the following questions to connect the concepts of this activity to the
NGSSS.
1.
Explain the role of activation energy in a reaction. How does an
enzyme affect activation energy?
2. Describe how a substrate interacts with an enzyme.
c. In a five-minute oral presentation, the students should share with the class
the results of their investigation. Here, they should state their hypothesis
and discuss whether their results confirm or refute their hypothesis. (Allow
for time to debate and discussion between groups.)
d. Have students complete a formal lab report.
Extension:
 Gizmo: Collision Theory
 Time permitting, you may choose to repeat the experiment with even higher or lower
concentrations.
 An interesting demonstration that can be performed for the class is to place a glowing
wooden splint in a beaker of hydrogen peroxide that has been catalyzed. The splint
should burst into flame. Students should relate their observations to the fact that the
presence of released oxygen gas ignites the splint. If a glowing splint is placed in uncatalyzed hydrogen peroxide, nothing happens.
Student
Enzyme Catalyst Lab
NGSSS:
SC.A.912.L.18.1 Describe the basic molecular structures and primary functions
of the four major categories of biological macromolecules.
(Also addresses SC.912.L.18.11)
Background:
This lab focuses on one particular enzyme – catalase. Catalase plays an
indispensable role in a living cell by preventing the accumulation of toxic levels of
hydrogen peroxide formed as a byproduct of metabolism. The enzyme, catalase,
speeds up the breakdown of hydrogen peroxide (H2O2) into water (H2O) and
oxygen gas (O2). The reaction is described by the following equation:
2 H2O2 → 2 H2O + O2
Problem Statement: How will different concentrations of hydrogen peroxide
affect the reaction of an enzyme?
Safety:
 Hydrogen peroxide is an oxidizer and could bleach clothing.
 Protect clothing by wearing a lab apron.
 Wear safety goggles
Vocabulary: activation energy, active site, enzyme, catalase, catalyst,
denaturation, enzyme, induced-fit model, rate of reaction, substrate
Materials (per group):
 Yeast solution
 Hydrogen peroxide
 Filter paper disks
 Forceps
 Eight 50 ml beakers
 Distilled water
 Marking pencil
 Paper towels
 Graph paper
Student
Procedures:
1. Make a hypothesis based on the problem statement.
2. Prepare peroxide solutions in separate test tubes as outlined in Table 1.
Table 1: Concentration Hydrogen Peroxide Solutions
Concentration
0% Peroxide Solution
25% Peroxide Solution
50% Peroxide Solution
75% Peroxide Solution
100% Peroxide Solution
Hydrogen Peroxide
0 ml
9 ml
18 ml
27 ml
35 ml
Distilled Water
35 ml
27 ml
18 ml
9 ml
0 ml
3. Using the forceps, dip a filter paper disk into the beaker containing the
solution of activated yeast. Keep the disk in the solution for 4 seconds,
and then remove it.
4. Place the disk on a paper towel for 4 seconds to remove any excess
liquid.
5. Using the forceps, transfer the filter paper disk to the bottom of a rubber
stopper.
Note: The yeast solution contains the catalase enzyme and when the
enzyme soaked disk comes into contact with hydrogen peroxide, the
reaction results in the formation of oxygen bubbles.
6. Insert the stopper into one of the test tubes and quickly invert the test
tube. Have one person in your group measure how long it takes for the
bubbles to carry the disk to the top of the test tube. Record the time in a
data table similar to the one shown below.
7. Repeat steps 2-5 until you have a minimum of three trials for each
peroxide solution.
8. Calculate the average rising time for each of the peroxide solutions.
Record this information in your data table.
9. Construct a graph plotting the concentration of hydrogen peroxide on the
x-axis (independent variable) and rising time on the y-axis (dependent
variable).
Observations/Data:
Table: Rising Time
Beaker
0% Peroxide
25% Peroxide
50% Peroxide
75% Peroxide
100% Peroxide
Trial 1
Trial 2
Trial 3
Average
Student
Data Analysis:
Construct and analyze a graph from your table.
Results/Conclusions:
1. Suppose you had placed a filter paper disk in a 30% peroxide solution.
Using your graph, predict how long it would take this disk to rise to the top.
2. In a paragraph describe how the concentration of peroxide affects the
breakdown rate of hydrogen peroxide. Use the results of this experiment
to justify your answer.
3. In a paragraph explain why your hypothesis was or was not supported.
4. Complete a formal laboratory report.