Biology/ Scholars Biology
Enzyme Controlled Reactions Virtual Lab Instruction Sheet
Introduction: As you have learned, enzymes are needed to initiate all the chemical reactions in living
organisms. In order for enzymes to function properly, both the pH and temperature of the organism are very
important and must be maintained within a narrow range. In this lab you investigate how pH and temperature
affect enzyme activity.
Purpose: To determine the effects of substrate concentration and pH on the rate of an enzyme catalyzed
reaction.
Procedure:
 Go to your biology page on pdecandia.com.
 Click on the organic chemistry picture and go to the lab section
 Click on the link for Enzyme Controlled Reactions (parts 1-2)
 Once on the virtual lab page, use the window on the left side of the page to read the procedure.
(use the scroll bar to read the directions)
 Follow the directions of the procedure to perform the virtual lab as listed below:
Part 1: Effect of pH on enzyme activity
1. Click the More Information button to read about enzymes and substrates.
- Answer the questions pertaining to this video clip in the lab report.
2. To begin the experiment, adjust the pH level of the test tubes by clicking the up and down arrows.
- The pH levels of the test tubes should be 3, 5, 7, 9, 11
3. Add a different amount of substrate to each of the test tubes that already contain an enzyme solution.
4. Click and drag a piece of weighing paper with the powdered substrate to a test tube.
5. Click the computer monitor to see the digital counter table that displays the number of product
molecules formed during the first minute in each of the five test tubes.
6. Record this information in the table 1 in your lab report.
7. Click the Reset button.
Part 2: Effect of different concentrations of substrate on enzyme activity
1. Change the pH of the test tubes so that all the test tubes have a pH of 3.
2. Add all the different substrates to each test tube.
3. Click the computer monitor to see the digital counter table that displays the number of product
molecules formed during the first minute in each of the five test tubes.
4. Record this information in the table 2 in your lab report.
5 Repeat the same activity at each of the different pH levels: 5, 7, 9, 11 and complete data table 3.
Part 3: The effect of temperature on enzyme activity
1. Go to pdecandia.com to your biology page, click on the organic chemistry link, go to the lab section.
2. Click on the link for Enzyme Controlled Reactions (part 3)
3. Read the information and watch the animations on temperature and enzyme activity.
4. Answer the questions for Part 3 in your lab report.
Name ______________________________
Scholars Biology Lab Report
Enzyme Controlled Reactions
Video Questions
1. At what place does the substrate bind to the enzyme in order for the enzyme to work? _____________________
2. Explain what happens when an enzyme catalyzes a reaction.
___________________________________________________________________________________
___________________________________________________________________________________
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3. Look up and write in the following definitions as they apply to chemical reactions:
a. Catabolic _______________________________________________________________
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b. Anabolic _______________________________________________________________
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c. Endergonic _____________________________________________________________
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d. Exergonic ______________________________________________________________
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4. Why is enzyme activity similar to a “Lock” and “Key”?
___________________________________________________________________________________
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Data
Table 1
pH
Amount of Substrate (g)
3
5
7
9
11
0.5
1.0
2.0
4.0
8.0
Number of Molecules of
Product Formed per Minute
Table 2
Amount of
Substrate
(Lactose)
0.5 g
1.0 g
2.0 g
4.0 g
8.0 g
pH 3
# Product Molecules/minute at:
pH 5
pH 7
pH 9
pH 11
Make a graph of Table 2
Data Analysis (Parts 1-2)
1. In both parts of the experiment identify the
Part 1
- independent variable ___________________________
- dependent variable ___________________________
Part 2
- independent variable ___________________________
- dependent variable ___________________________
2. Which amount of substrate produced the most molecules? __________________
3. Which amount of substrate produced the least molecules ___________________
4. Which pH level was the most ideal to turn the substrate into molecules? ___________________
5. Which amount of substrate resulted in amounts of product that were the same? __________________
6. What happens to the reaction rate as substrate concentration increases?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
7. What was the temperature for each trial? _________________
8. What pattern kept showing up in the test tubes where you added the 4g and 8g substrate?
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9. What does this same about this substrate when put into any pH level?
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10. After analyzing your data, what conclusion can you come to about pH and enzyme activity?
___________________________________________________________________________________
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11. After analyzing your data, what conclusion can you come to about substrate amount and enzyme activity?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
12. Enzymes function most efficiently at the temperature of a typical cell, which is 37 degrees Celsius.
Increases or decreases in temperature can significantly lower the reaction rate. What does this suggest
about the importance of temperature-regulating mechanisms in organisms? Explain.
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Analysis Questions Part 3
1. Explain what happens to the shape of enzyme and its active site when exposed to high temperatures?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
2. Once this change occurs, will the enzyme return to its original condition, and can it be used again?
___________________________________________________________________________________
3. What is this process called? ________________________________
Name ______________________________
Biology Lab Report
Enzyme Controlled Reactions
Video Questions
1. At what place does the substrate bind to the enzyme in order for the enzyme to work? _____________________
2. Explain what happens when an enzyme catalyzes a reaction.
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
3. Why is enzyme activity similar to a “Lock” and “Key”?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
Data
Table 1
pH
Amount of Substrate (g)
3
5
7
9
11
0.5
1.0
2.0
4.0
8.0
Number of Molecules of
Product Formed per Minute
Table 2
Amount of
Substrate
(Lactose)
0.5 g
pH 3
# Product Molecules/minute at:
pH 5
pH 7
3.0 g
4.0 g
5.0 g
8.0 g
Data Analysis (Parts 1-2)
1. In both parts of the experiment identify the
Part 1
- independent variable ___________________________
- dependent variable ___________________________
pH 9
pH 11
Part 2
- independent variable ___________________________
- dependent variable ___________________________
2. Which amount of substrate produced the most molecules? __________________
3. Which amount of substrate produced the least molecules ___________________
4. Which pH level was the most ideal to turn the substrate into molecules? ___________________
5. Which amount of substrate resulted in amounts of product that were the same? __________________
6. What happens to the reaction rate as substrate concentration increases?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
7. What was the temperature for each trial? _________________
10. After analyzing your data, what conclusion can you come to about pH and enzyme activity?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
11. After analyzing your data, what conclusion can you come to about substrate amount and enzyme activity?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
Analysis Questions Part 3
1. Explain what happens to the shape of enzyme and its active site when exposed to high temperatures?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
2. Once this change occurs, will the enzyme return to its original condition, and can it be used again?
___________________________________________________________________________________