Transcript CAPT Lab: Investigating the Effect of Temperature on Enzyme Activity

CAPT Lab:
Investigating the Effect of
Temperature on Enzyme Activity
Created by Mr. Cross - 2007
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.
Directions
Read through the presentation and answer
the questions as they are proposed.
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.
Activation energy
without enzyme
Reaction pathway
without enzyme
Reactants
Reaction pathway
with enzyme
Products
Activation
energy
with enzyme
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.
Problem Statement
How does temperature affect the
rate of an enzyme catalyzed
reaction?
Materials
Raw liver
Petri dish
Dropper pipette
50 mL Beakers
1 % Hydrogen Peroxide
Solution
25 mL graduated
cylinder
Filter-paper disks
Glass marking pencil
Ice bath
3 thermometers
Warm water bath
Clock or stop watch
Forceps
Liver Puree
Hot plate
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.
2H2O2 (aq)  2H2O (l) + O2 (g)
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.
Your Task
• Design an experiment to test the affects of
temperature on enzyme activity.
Write a Hypothesis
Sample Hypothesis:
As the temperature of an enzyme’s
environment increases the rate of the
catalase reaction will decrease.
What is the independent variable
(manipulated variable)?
Temperature
What is the dependent variable
(responding variable)?
Rate of the reaction
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
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.
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.
The following data was
recorded by the student
Water
Environment
Cold
Temperature
(Celsius)
2
Seconds to
Float
35 seconds
Room
Temperature
Luke warm
18
15 seconds
26
5 seconds
Warm
40
3 seconds
Hot
49
Did not Float
Student 1’s Graph
The Affect of Temperature on Catalse Activity
40
Time to Float (s)
35
35
30
25
20
15
15
10
5
5
3
0
0
10
20
30
40
Temperature (Celsius)
Note: 49 degrees Celsius never floated.
50
60
Student 2’s Graph
The Effect of Temperature on Catalase
Activity
Temperature
60
50
40
3
30
5
20
15
10
35
0
0
10
20
Time (s)
30
40
State which graph is better and provide reasons.
The Affect of Temperature on Catalse Activity
The Effect of Temperature on Catalase
Activity
35
30
35
60
25
20
15
10
Temperature
Time to Float (s)
40
15
5
0
5
3
50
40
3
30
5
20
15
10
35
0
0
10
20
30
40
50
60
0
Temperature (Celsius)
10
20
30
Time (s)
Note: 49 degrees Celsius never floated.
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.
40
What conclusions can be drawn from Student 1’s Data?
The Affect of Temperature on Catalse Activity
Time to Float (s)
40
35
30
35
25
20
15
10
15
5
0
5
0
10
20
3
30
40
50
60
Temperature (Celsius)
Note: 49 degrees Celsius never floated.
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.
What could be done to improve the
validity of the experiment?
• Increase the number of trials at each
temperature.
What further investigations could be done?
• Investigate the affects of temperature at
the 30 - 60 degree Celsius range.
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?
The Affect of Temperature on Catalse Activity
Time to Float (s)
40
35
30
35
25
20
15
10
15
5
0
5
0
10
20
3
30
40
Temperature (Celsius)
50
60
Yes it does. The
graph clearly shows
that the enzyme
activity is at its
greatest between
30 – 40 degrees
Celsius.