Penny Wars: An Enzyme - Substrate Model Learning Targets

1. I will be able to list and explain factors that affect the reaction rates of an enzyme-mediated reaction 2. I will collect, graph and analyze data relating to the reaction simulated in this activity.

Materials: For a group of 4 students: 80 pennies, one stop watch, masking tape, two tennis balls Procedure: TRIAL 1 - NO ENZYME Students should organize into 4 person teams. 80 pennies should be turned tail side up at one end of the lab bench. One member of each team will attempt to pick up as many pennies as possible turning each one so that the head side is facing up on a mat to the opposite end of the lab bench. Since this reaction will NOT be catalyzed by an enzyme, you may NOT use your hands or fingers to pick up or flip the pennies. This process will be done 6 times for a period of 10 seconds each time. Do not return pennies to the original pile between timing intervals. Other team members will count and record the number of pennies recovered in each trial period. Record your data in the results section of your analysis sheet (Table 1). TRIAL 2 - BASELINE After the pennies have been redistributed on the bench, a different member of your group will have the task of picking up pennies and turning them to the head side up in order to get a baseline rate for this reaction with an enzyme (now it is okay to use your fingers and hands!) He or she will attempt to pick up as many pennies as possible, turning each one so that the head side is facing up. Record your data in the results section of your analysis sheet (Table 1). TRIAL 3 - DENATURATION After the pennies have been redistributed on the bench, a different member of your group will have the task of picking up pennies and turning them to the head side up. In this trial the hand used to select the pennies will have the thumb taped to the palm, representing the partial denaturation (change in shape) of the enzyme. Enzymes, like all proteins, tend to change shape at high temperatures, when in contact with strong acids or bases, or when exposed to heavy metal ions. How well do you expect to do in picking up pennies compared to Trial 1? Let's see. Record your data in the results section of your analysis sheet (Table 1). TRIAL 4 - ROLE OF COFACTOR After the pennies have been returned to the bench, the next team member will perform the penny selecting task. However, this time he/she will have the help of a teammate, representing the role of a coenzyme. The student picking up pennies merely has to pick them up and give them to his/her partner and they will be responsible for turning them head side up. This last process by the helper may extend beyond the 10 second interval. As before, six time periods will be used. Record your data in the results section of your analysis sheet (Table 1). TRIAL 5 - COMPETITIVE INHIBITORS In this last trial any one member of the team who wishes will retrieve pennies as before but will be handicapped by the presence of a tennis ball or some other object in the palm of the hand to be used. Obviously, this object may interfere with your ability to pick up pennies. The ball or object represents an inhibitor which is competing with the place on your hand where you pick up the pennies. Try it for six time periods and see what happens. Good luck! Teammates, please record your data in the results section of your analysis sheet (Table 1)

BILL # :Penny Pickers Modeling Enzyme-Substrate Interactions

PreLab Define the following terms.

1. Enzyme:

2. Active site:

3. Substrate:

4. Coenzyme-

5. Competitive inhibition:

6. Denaturation: Label the diagram below:

Results Table 1 Time interval (sec)

Trial 1 No enzyme # of pennies Total

Trial 2 Baseline

# of pennies Total

Trial 3 Denaturation # of pennies Total

Trial 4 Coenzyme

# of pennies Total

Trial 5 Competitive

Inhibition # of pennies Total

0-10

10-20

20-30

30-40

40-50

50-60

Penny # = Number of pennies picked up in each specific time interval Total= cumulative total of all the pennies picked up so far in the trial. ** Note: Once you get “0” pennies for a time interval, the cumulative total should be entered for zero as well.

Prepare a graph of your team’s on the graph paper provided.

• Plot Total # captured vs. time interval for each Trial. • The result will be a multi-line graph, (five lines; one for each trial). • Choose a different color for each Trial. • Provide a key. • Give your graph a descriptive title. • Label the X and Y axis (include units if applicable)

1. What is the independent variable? __________________________ 2. What is the dependent variable? ____________________________

Hint: Plot the IV on the X axis, and DV on the Y axis. Title__________________________________________________

Conclusions 1. In this activity, what was the enzyme represented by? ___________________

The substrate? ___________________________

The coenzyme? _________________________

The inhibitor? ____________________________

2. In trial 2, did the rate eventually decrease? __________ Why? ________________________________________________________

3. If more substrate were present in Trial 2 at the beginning, would the initial rate have been higher? _________ Why or why not? ______________________________________________

4. If we assume that the enzyme is represented by the hand, what happened to the active site during Trial 3?

5. Why does an enzyme not work as well if its active site is changed?

6. According to your data, how did the addition of a coenzyme affect reaction rates?

7. What type of substance typically acts as a coenzyme? (See notes/ text if you are unsure)

8. List some environmental factors affect enzyme activity. (See notes/ text if unsure)

9. What effect did inhibition have upon the reaction rate?

10. Heavy Metals, such as mercury and lead are chemical inhibitors. How might these chemicals affect your reaction rates if they act like the tennis ball (inhibitor) as your cells try to maintain homeostasis?