Glencoe virtual lab enzyme controlled reactions

WEEK 2 EXPERIMENT ANSWER SHEET Please submit to the Week 2 Experiment dropbox no later than Sunday midnight.

SUMMARY OF ACTIVITIES FOR WEEK 2 EXPERIMENT ASSIGNMENT

· Experiment 2 Exercise 1a – Effect of substrate concentration on enzyme function

· Experiment 2 Exercise 1b – Effect of pH on enzyme function

· Experiment 2 Exercise 2 – Cellular Respiration and Photosynthesis

Experiment 2 Exercise 1A: Effect of substrate concentration on enzyme function

Review the Week 2 Experiment Introductions, our online lecture on Energetics and pp 80 - 82 in your book. For this exercise, we are going to look at the effect of substrate concentration on enzyme function, while holding enzyme concentration, pH and temperature constant. Open the following website to get started:

Glencoe- McGraw Hill. No date. Enzyme-controlled Reactions http://glencoe.mcgraw-hill.com/sites/dl/free/0078759864/383930/BL_11.html

Procedure

A. Click on the TV/VCR and listen to the short overview about enzyme action. Close the window when done.

B. Then click on the Information button and review the information there. Close the window when done.

C. In our first experiment, we will determine the effect of different amounts of substrate on enzyme function. First, we need to set up the experiment:

a. Click on the 0.5 g substrate weigh paper and drag it to Tube #1; note the color change. When our enzyme breaks down the substrate, the solution turns blue. The intensity of the color indicates the amount of product formed.

b. Now drag the 1.0 g substrate weigh paper to Tube #2 and continue as such with the rest of the substrate samples as indicated in the table below.

c. Click on the computer monitor to view your results and transcribe them to Table 1 below.

Table 1. Substrate amount and product formation results (1 pts).

Test Tube Number

Amount of Substrate (g)

# of Molecules of Product Formed per Minute (X 106)

1

0.5

2

1.0

3

2.0

4

4.0

5

8.0

D. Generate a scatter plot of Amount of Substrate vs Molecules of Product Formed and paste it here. Be sure you label your axes and include units. If you need help generating a graph, see the tutorials mentioned in the Week2 Experiment Introduction (3 pts).

Questions

1. In this Experiment, which variable is the dependent variable and which is the independent variable (2 pts)?

2. Describe the relationship between substrate concentration and enzyme function (as estimated by product formation) as evidenced by your graph above (1 pts).

3. What is the maximum rate of product formation and at what substrate level did this occur (1 pts)?

Experiment 2 Exercise 1b: Effect of pH on enzyme function

Be sure to review the Week 2 Experiment Introduction, our online lecture on Energetics and pp 80 - 82 in your book. For this experiment, we are going to look at the effect of pH on enzyme function, while holding enzyme concentration, substrate concentration and temperature constant. Go to:

Enzyme-controlled Reactions http://glencoe.mcgraw-hill.com/sites/dl/free/0078759864/383930/BL_11.html

Procedure

A. Click on Reset if necessary before beginning.

B. In our second experiment, we will determine the effect of pH on enzyme function. First, we need to set up the experiment:

a. First, you will need to adjust the pH in each test tube.

i. Use the up or down arrows beneath the test tubes.

ii. Set Tube #1 at pH 3 and Tube #2 to pH 5. Leave Tube #3 at pH 7. Set Tube #4 to pH 9 and Tube #5 to pH 11.

iii. Your test tube rack should now look like this:

image1.png

C. Click on the paper containing 4.0 g of substrate and add it to each tube. Note that the amount of substrate is now a control variable and we add the same amount of substrate to each tube.

D. Click on the computer to view your results and transcribe your data to Table 2 below.

Table 2. pH and product formation amounts (1 pts).

Test Tube Number

pH

# of Molecules of Product Formed per Minute (X 106)

1

3

2

5

3

7

4

9

5

11

E. Generate a scatter plot in of pH vs Molecules of Product Formed and paste it here. Be sure you label your axes and include units (3 pts).

Questions

1. In this Experiment, which variable is the dependent variable and which is the independent variable (1 pts)?

2. Describe the relationship shown in your graph between pH and enzyme activity. At what pH did you see optimum enzyme activity (2 pts)?