Enzyme Activity Lab
Teacher Instruction
Part 1: Temperature and enzyme activity
Students will be examining the effects of various temperatures on the activity of the
enzyme catalase in potatos and determine the optimal temperature. Teachers should
prepare 6 water baths in advance, 1 at each station, of temperatures 0°C, 10°C, 20°C,
37°C, 50°C, and 100°C. Depending on the class size, students will be divided into
groups of 3s or 4s and assigned to a station. They will then mix a piece of potato, and
hydrogen peroxide to rank the reaction rate. The class results will then be pooled and
distributed.
It may be helpful to pool data from different classes and distribute the ones in consensus
to avoid foul play.
Part 2: pH and enzyme activity
Students will be examining the effects of various pH on enzyme activity and determine
the optimal pH. Students will set up 5 test tubes for this part, mixing catalase, a specific
pH solution, and hydrogen peroxide. They will then rank the rate of reactions. The
specific pHs used will be 1, 4, 7, 10, and 13.
Materials
Small graduated cylinder
3% H2O2
hot plate
pH solutions
masking tape
beakers
cork borer
ice/ice water
test tube rack
5-6 test tubes
scalpel
thermometer
potato
Safety Concerns
Hydrogen Peroxide 30% MSDS:
<http://www.sciencelab.com/msds.php?msdsId=9924299>
*Make sure hot plates are turned off once students are done using them*
**strong bases and acids should be handled with care**
Students’ Alternate Conceptions




The higher the temperature, the higher the enzyme activity or the lower the enzyme
activity
Enzymes ONLY work at a specific pH
Denaturing and inactive are interchangeable terms
pH or temperature VS. reaction rate is a linear relationship, either positive or
negative
Diagnostic Assessment
What I Know
Before…(point form is
fine)
Topic
What I Know After… (to
be completed after lab for
submission)**
What is an inactive
enzyme?
An inactive enzyme is a state
of an enzyme where it does
not fit its substrate hence does
not increase the rate of
reaction.
Denaturing is the permanent
loss of shape by the enzyme
which is irreversible
There is an optimal pH the
enzyme works best at.
Extreme pHs makes the
enzyme inactive and possibly
denature. The relationship is
of a bell curve nature.
There is an optimal
temperature the enzyme works
best at. Extreme temperatures
make the enzyme inactive and
possibly denature. The
relationship is of a bell curve
nature.
What does the term
denature mean?
What is the relationship
between various pH of
solutions and rate of
enzyme reaction?
What is the influence of
temperatures on rate of
enzyme reaction?
**This column is to be completed by students after the investigation. The answers
provided are guidelines for teachers as to what the expectations are.
Assessment Strategy
1. Complete the diagnostic chart after performing the investigation.
2. Informal Lab Report:
Tables
2 Graphs
Discussion (possible things to address can be but not limited to):
 What was the control solution?
 The effects of varying pH and temperature on reaction rate?
 Are there any pH or temperature catalase works best at? What is that value called?
 Were there any effects by very strong acids or bases on the enzyme? How?
 What was the reaction rate for near boiling conditions? What was the reaction for
near freezing-point conditions?
 Are there any similarities between catalase in potatoes and enzymes in humans?
 Did the results agree your “what did I know before…” column? Why or why not?
Other optional headings: What did you do? (ie. procedures) What was the purpose of
the experiment? What were some possible errors?
Enzyme Activity Lab
Student Instructions
Background
Catalase is an enzyme found in potatos and many other living organisms. This enzyme
breaks down hydrogen peroxide. Hydrogen peroxide can often be found as a waste
product in the cellular respiration pathway. The breakdown reaction generates oxygen gas
and water. In this investigation, the relative reaction rate of catalase is going to be
measured from the amount of oxygen gas produced while paying attention to the effects
of varying pHs and temperatures.
Materials
Small graduated cylinder
3% H2O2
hot plate
pH solutions
masking tape
beakers
cork borer
ice/ice water
test tube rack
5-6 test tubes
scalpel
thermometer
potato
Part 1: Temperature study
1.
2.
3.
4.
5.
6.
7.
8.
9.
Use cork borer to cut potato into equal diameter pieces. Cut out a ~2-cm piece.
Place one piece of potato into a test tube.
Add just enough water into test tube to cover potato
Place your test tube into your assigned premade water bath temperature for about 5
min. Caution: Do not touch hot plate if that applies to you.
Remove test tube from water bath and pour out water in test tube without pouring out
the potato. Use forceps if removing from hot water.
Add 5 mL of 3% hydrogen peroxide and record amount of bubbling. Use ranking
system from 0 (no reaction) to 5 (lots of bubbling). Use your judgement.
Make any other observations as needed.
Pool your data with the rest of the class on the chart on the blackboard.
Discard the potato piece when reaction is complete.
Part 2: pH study
1.
2.
3.
4.
5.
6.
Use cork borer to cut potato into equal diameter pieces. Cut out 5 or 6 ~2-cm pieces.
Place one piece of potato into each test tube.
Label each test tube with its designated pH
Place 5 mL of each pH solution into their designated test tubes
After about 5 minutes, pour out liquid but keep potato piece in test tube.
Add 5 mL of 3% hydrogen peroxide and record amount of bubbling. Use ranking
system from 0 (no reaction) to 5 (lots of bubbling). Use your judgement.
7. Make any other observations as needed.
8. Discard the potato piece when reaction is complete.
Source of Activity
Modified from:
Safia Merali
Grade 12 Biology Teacher, Albert Campbell CI. Toronto, ON.
Resources
Protein as Catalysts, Environments: <http://resources.schoolscience.co.uk/unilever/1618/proteins/Protch6pg4.html>
Dippin’ Dots o’ Enzyme (another modified enzyme activity lab, investigating other
factors that may impact reactivity. Also measures reactivity output in a more accurate but
still indirect approach with filter paper):
<http://www.dc.k12.mn.us/teacher_websites/high_school/peterson/index_files/Lab%20w
ork/Enzyme%20Catalysis%20Yeast.pdf>
Investigating the Effects of Surface Area on the Rate of Enzyme Reactions
<http://www.123helpme.com/view.asp?id=120983>
Links to Ontario Curriculum
B2.5 plan and conduct an investigation related to a cellular process (e.g., factors that affect
enzyme activity; factors that affect transport of sub- stances across cell membranes), using
appropriate laboratory equipment and techniques, and report the results in an appropriate
format [IP, PR, C]
B3.4 describe the chemical structures and mech- anisms of various enzymes