Name: __________________________________ Period: ___ Date: ___ / ___ / ___
Virtual Enzyme Activity
Background Information:
This virtual lab is able to simulate the effects of pH and substrate concentration level on an enzyme’s
ability to catalyze a reaction. To complete this virtual enzyme lab you need to go to the website
below. You may want to just click on the link on my weebly (under today’s date).
http://glencoe.mcgraw-hill.com/sites/dl/free/0078695104/383930/BL_11.html
Procedure:
Part 1: pH
1. Click on the computer monitor to display the data table.
2. Change the pH of test tubes so all 5 are at a different pH. Use the following table to help.
Test Tube Number pH
1
3
2
5
3
7
4
9
5
11
3. Add 2.0 g of substrate to each test tube.
4. Use the data in the data table to create an XY scatter plot graph in Excel. Click on the computer
to generate the data.
a. Graph the independent variable (the variable you can control) on the X-axis.
b. Graph the dependent variable (the variable that is different because of the experiment) on
the Y-axis.
c. Be sure to title the graph and include labels with units on each axis.
d. Call your teacher over to check your graph.
5. Record the pH(s) where the enzyme is most affective here: _______
6. Explain why you made that choice.
Part 2: Amount of Substrate
1. Repeat the experiment. This time use the pH that was most affective from Part 1.
2. Click on the computer monitor to display the data table.
3. Make sure the pH in all of the test tubes is identical (a constant in all test tubes). Use the pH that
was most affective from Part 1.
4. Add different amounts of substrate to each test tube. Use the following table to help.
Test Tube Number Amount of Substrate (g)
1
0.5
2
1.0
3
2.0
4
4.0
5
8.0
5. Use the data in the data table to create an XY scatter plot graph in Excel. Click on the computer
to generate the data. Follow the same directions for graphing as in Part 1.
6. Call your teacher over to check your graph.
7. Record the amount(s) of substrate where the enzyme is most affective here: _______
8. Explain why you made that choice.
Conclusion Questions:
Answer the following questions using complete sentences.
1) Now, analyze the data you collected and graphed. What conclusions can you draw about the
effects of a changing pH on enzyme activity/reaction rate? What conclusions can you draw about
the effects of a changing the amount of substrate on enzyme activity/reaction rate? Use your data
(NUMBERS) to defend your response. (You should refer to multiple data points.)
2) What is happening to the enzyme structure as the pH changes to cause the enzyme activity to
change? In other words, what changes about the enzyme that causes the rate of the reaction to
change? (You may have to do some outside research to answer this question.)
3) Why is the enzyme more affective as more substrate is added? Why does the effectiveness of the
enzyme level out as a very high amount of substrate is added?
4) You have seen the effects of changing the pH and amount of substrate on enzyme activity. Now
make a prediction on what your results would look like if you ran the experiment changing the
temperatures of the test tubes. Create a hypothetical graph below showing the amount of product
formed (rate of reaction, 0-10) based at different temperatures ranging from (0° C to 100° C). The
x-axis should show the temperature. On the y-axis, “0” indicates no activity (no molecules of
product formed), “1” indicates very low activity (a few molecules of product formed), and 10
indicates very high activity (lots of molecules of product formed).
5) Speculate why there is an optimum temperature and pH level for enzyme activity.
(Hint: think of the human body.)