Title: Enzymes Lab
Purpose
• To simulate the effects of pH, temperature, and enzyme concentration on the activity of
different enzymes.
• To determine the optimal (best) conditions for each of the enzymes.
Hypothesis:
This lab will allow you to determine optimal conditions for the function of various enzymes
and you will develop your hypotheses about the conditions for each enzyme as your
conclusion.
Materials:
OnLine Enzymes Interface
(See below for background information on using the Enzymes Interface)
Procedure:
1. Go to http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch06expl.htm
2. Click Skip Intro
3. Click on the New Enzyme button until B-galactosidase appears at the top of the screen.
4. Enzyme Concentration
a. Set the relative enzyme concentration to 0.2.
b. Click the Plot Point button.
(The point that appears on the graph indicates the rate of reaction for this enzyme
concentration, expressed as a percentage of Vmax, the highest possible reaction rate)
c. Record the reaction rate in Data Chart A
d. Now set the relative enzyme to 0.0 and click the Plot Point button. Record
e. Repeat for the relative enzyme concentrations indicated in Data Chart A.
f. When you have finished, click on the New Enzyme button and repeat the above
procedure with carbonic anhydrase, and then for the enzymes indicated in Data
Chart A.
g. Graph Enzyme Concentration (x-axis) vs Reaction Rate (y-axis) using Create a
Graph (http://nces.ed.gov/nceskids/graphing )
h. Print and paste your graph after the data chart in your Lab Notebook.
5. Temperature
a. Set the temperature to 0oC.
b. Click the Plot Point button.
c. Record the reaction rate in Data Chart B
d. Now set the temperature to 10oC and click the Plot Point button. Record.
e. Repeat for the temperatures indicated in Data Chart B.
f. When you have finished, click on the New Enzyme button and repeat the above
procedure with carbonic anhydrase, and then for the enzymes indicated in Data
Chart B.
g. Graph Temperature (x-axis) vs Reaction Rate (y-axis) using the using Create a
Graph (http://nces.ed.gov/nceskids/graphing )
h. Print and paste your graph Paste your graph after the data chart in your Lab
Notebook.
Judith S. Nuño
AP Biology
2005/2006
6. pH
a.
b.
c.
d.
e.
f.
Set the pH to 3.
Click the Plot Point button.
Record the reaction rate in Data Chart C
Now set the pH to 4 and click the Plot Point button. Record.
Repeat for the pH values indicated in Data Chart C.
When you have finished, click on the New Enzyme button and repeat the above
procedure with carbonic anhydrase, and then for the enzymes indicated in Data
Chart C.
g. Graph pH (x-axis) vs Reaction Rate (y-axis) using Create a Graph
(http://nces.ed.gov/nceskids/graphing )
h. Print and paste your graph Paste your graph after the data chart in your Lab
Notebook.
Results:
Data Chart A: Effect of Relative Enzyme Concentration on Reaction Rate
Relative
Carbonic
B-galactosidase
Chymotrypsin
Lysozyme
Enzyme
Anhydrase
% of Vmax
% of Vmax
% of Vmax
% of Vmax
Concentration
0.0
0.2
0.4
0.6
0.8
1.0
Penicillinase
% of Vmax
Paste your graph after the data chart in your Lab Notebook
Data Chart B: Effects of Temperature on Reaction Rate
Carbonic
Temperature B-galactosidase
Chymotrypsin
o
Anhydrase
C
% of Vmax
% of Vmax
% of Vmax
Lysozyme
Penicillinase
% of Vmax
% of Vmax
0
10
20
30
40
50
Paste your graph after the data chart in your Lab Notebook
Data Chart C: Effect of pH on Reaction Rate
Carbonic
B-galactosidase
pH
Anhydrase
% of Vmax
Chymotrypsin
Lysozyme
Penicillinase
% of Vmax
% of Vmax
% of Vmax
% of Vmax
3
4
5
6
7
8
Paste your graph after the data chart in your Lab Notebook
Judith S. Nuño
AP Biology
2005/2006
Discussion:
(Summarize what you did, describe your results, indicate whether or not you met your
purpose or supported your hypothesis, indicate sources of error, and suggest
improvements in the experimental design.
Also, indicate how the specific function of each enzyme is related to its optimal conditions
by answering these questions:
1. Which enzyme functions best in an acidic environment? (Remember, an acidic
environment has a low pH value).
2. Which enzyme (s) functions best over the broadest pH range?
3. In general, how does the amount of enzyme present affect the reaction rate for the
enzymes?
Conclusion: (Use the following statements and fill in the blanks for each enzyme)
The optimal conditions for B-galactosidase are a pH of ______, temperature of _____,
and an enzyme concentration of _______.
The optimal conditions for chymotrypsin are a pH of ______, temperature of _____, and
an enzyme concentration of _______.
The optimal conditions for carbonic anhydrase are a pH of ______, temperature of
_____, and an enzyme concentration of _______.
The optimal conditions for lysozyme are a pH of ______, temperature of _____, and an
enzyme concentration of _______.
The optimal conditions for penicillinase are a pH of ______, temperature of _____, and
an enzyme concentration of _______.
Reflection:
(Personal commentary about what you learned from the lab simulation)
Data Chart D: Effects of Temperature, pH, and Enzyme Concentration on the Reaction
Rate of B-galactosidase.
Temperature Reaction Rate
Enzyme
Reaction Rate
Reaction Rate
pH
o
% of Vmax
% of Vmax
% of Vmax
Concentration
C
Judith S. Nuño
AP Biology
2005/2006
How to Use the Enzymes OnLine Lab
This interactive exercise allows you to explore the way in which reaction conditions affect
how an enzyme catalyzes a chemical reaction, focusing on the key roles of enzyme
concentration, temperature, and pH. Every enzyme has a characteristic rate and a unique
sensitivity to temperature and pH, all of this behavior depending upon its particular structure. In
this interactive exercise, you can investigate the nature of this dependence for several real
enzymes. First you select an enzyme to be investigated, and then you select values for enzyme
concentration, temperature, or pH, and observe the effects on reaction rate. The three variables
taken together provide quite a realistic view of the operating behavior of the enzyme. By
comparing different enzymes, you will gain learn how well enzymes are suited to the physiological
conditions under which they operate.
Click on the Skip Intro button, located in the lower right-hand corner, to start the OnLine
Lab. This simulation allows you to manipulate three critical parameters for five common enzymes
encountered in the human body. On the screen before you are three boxes labeled "enzyme
concentration," "temperature," and "pH." These are the parameters you will have the opportunity
to alter. The bar across the top of the screen tells you which enzyme you are altering. To see how
altering enzyme concentration, temperature, and pH affect the reaction rate of catalysis, which is
how fast the enzyme does what it's supposed to be doing, you will plot a series of five points for
each parameter on its corresponding scale.
To plot a point, click on the slider triangle in one of the three slides at the lower left hand
corner of your screen and drag it to a desired value, then use the mouse to click on the large "plot
point" button at the bottom of the box. When you do this, a red plot point will appear on the
appropriate scale. At the same time, the "reaction rate" meter in the upper left hand corner will
show you how quickly the reaction is proceeding at the value you have selected. Repeat this four
more times. When you have plotted a total of five points, the computer will allow you to plot a
graph. Click on the plot graph button to see how your graph looks.
When you have finished with all three parameters, take a look at the screen. You've
created an "activity profile" of the enzyme you are examining. An activity profile predicts how that
enzyme will behave under a broad range of conditions. Can you tell what the optimum enzyme
concentration, temperature, and pH are by looking at your graphs? Does any one parameter
seem to be more critical or sensitive than the others? After you're finished with your first enzyme,
click on the "New enzyme" button above the "plot graph" button. This will clear your scales and
give you an entirely new enzyme to manipulate. Repeat the procedures until you have collected
data for all five test enzymes. Use the Week 2 Enzymes Template to record your results and
complete your lab report.
Judith S. Nuño
AP Biology
2005/2006