Name:______________________________
_____/25 points
TOOTHPICKASE LAB ACTIVITY
Background: Enzymes are proteins that help speed up (catalyze) chemical reactions without being used
up or changed by the reactions. Enzymes are able to increase the rate of chemical reactions by lowering
the activation energy to start the reaction. Each enzyme is specifically designed to fit with a specific
substrate and the enzyme and substrate link at the active site. Various factors impact enzyme activity
including pH, temperature, salinity and concentration of the enzyme and/or substrate.
In this activity, your hand will represent “toothpickase”, an enzyme that aids in breaking apart
toothpicks (the substrate). Your thumb and forefinger represent the active site at which the toothpick
can be broken. Enzymes work randomly, so to model this you will complete all tasks with your eyes
closed. During this activity, you will examine “normal” toothpickase activity and the impact of
increased enzyme concentration and temperature on enzyme activity.
Ground Rules:
 Only ONE toothpick may be broken at a time.
 The toothpick must be broken COMPLETELY in half, or it does not count as a product.
 Each broken toothpick must go back into the original pile (simulating that products and reactants
continue mixing during the reaction).
 Complete all rounds with your eyes CLOSED (simulating the random interactions of enzymes)
Problem: How does changing enzyme concentration, substrate concentration, or temperature/pH affect
the reaction rate of enzyme activity?
Procedure:
Part I:
1.
2.
3.
4.
Count out 50 toothpicks.
Spread the toothpicks out in your green bin.
Timer, get the stopwatch ready.
When the timer says “GO”, toothpickase will break as many toothpicks as possible (following
the rules above).
5. After 60 seconds, when the timer says “STOP”, toothpickase will stop and the counter will count
how many toothpicks were broken. (Remember, the toothpick must be broken COMPLETELY
in half to count as a product.)
6. The data recorder will record the total number of toothpicks broken in table 1.
7. Throw out broken toothpicks, save unbroken toothpicks for next part of procedure.
Part II:
Prediction:__________________________________________________________ (1 pt.)
1. Repeat everything from Part I, but this time count out 100 toothpicks. Keep the toothpicks
spread out in a small area, as in Part I. These rounds simulate what happens when substrate
concentration is doubled. Record data from Part II in Table 2.
Part III:
Prediction:__________________________________________________________ (1 pt.)
1. Repeat everything from Part I, but this time have two group members act as toothpickase (break
toothpicks). Keep the toothpicks spread out in a small area, as in Part I. These rounds simulate
what happens when enzyme concentration is doubled. Record data from Part III in Table 3.
Part IV: Prediction:__________________________________________________________ (1 pt.)
Repeat everything from Part I, but this time have a group member tape toothpickase’s thumbs across
their palms as demonstrated by the teacher. These rounds simulate what happens when enzyme shape is
changed due to a change in pH or temperature. Record data from Part IV in Table 4.
Table 1:
Toothpickase Activity – Normal Conditions (Optimal pH & Temp.) – 2 points
Number of toothpicks broken
Table 2:
Toothpickase Activity – Doubled Substrate Concentration – 2 points
Number of toothpicks broken
Table 3:
Rate of reaction (number of
toothpicks broken/sec.)
Rate of reaction (number of
toothpicks broken/sec.)
Toothpickase Activity – Doubled Enzyme Concentration – 2 points
Number of toothpicks broken
Rate of reaction (number of
toothpicks broken/sec.)
Table 4: Toothpickase Activity – Change in Enzyme Structure (due to change in pH or temp.) – 2
points
Number of toothpicks broken
Rate of reaction (number of
toothpicks broken/sec.)
Calculations:
1. Calculate the reaction rate for each simulation
Formula:
Total # of Toothpicks Broken
Time in seconds
=
Reaction Rate
Toothpickase Lab
Conclusion Questions:
1. (3 points) In this activity…
What represented the enzyme? ____________________________________________________
What represented the substrate? __________________________________________________
What represented the active site? __________________________________________________
2. What happened to the reaction rate when the substrate concentration was doubled? Why? (2
pts.)
3. What happened to the reaction rate when the enzyme concentration was doubled? Why? (2 pts.)
4. What happened to the reaction rate when the enzyme shape was changed? Why? (2 pts.)
5. What would happen to toothpickases’ ability to break “molecules” in half if I gave you pipe
cleaners to break instead of toothpicks? How does this mimic enzyme activity? (2 pts.)
6. Changes in ____________ or _______________ decrease enzyme activity by changing the
enzyme’s _______________________. (3 pts.)