Toothpick Biochemistry: Toothpickase
Introduction:
Enzymes are proteins that are used as catalysts in biochemical reactions. A catalyst is
something that controls the rate of a reaction without itself being used up. Often enzymes
are used to speed up the rate of a reaction. However, there are at least two things that can
affect the rate of a reaction: 1) substrate formation, and 2) temperature. Here is a set of
activities designed to simulate how substrate concentration and temperature affect
enzyme function.
In those activities that follow:
 one person’s fingers are the enzyme TOOTHPICKASE
 the toothpicks are the SUBSTRATE
 to hydrolyze the toothpick, place a toothpick between the thumb, first finger and
middle finger of one hand. Break the toothpick in two pieces.
Procedure:
The Rules:
1. You must break each toothpick one at a time
2. You must break each toothpick with one hand ONLY.
3. You must break each toothpick completely in half.
4. You cannot begin before the timer calls Go!
5. You must stop precisely when timer says STOP!
Part A: Enzyme Activity
1. Pick up a toothpick between the thumb and the index finger of one hand.
Hydrolyze the toothpick by breaking it in two pieces using the thumb, index
finger and middle finger.
a. What is the substrate?
b. If your hand is the enzyme, describe the “active site”.
c. Is the enzyme used up after performing the reaction, or is it available to
perform another reaction?
d. What are the products of this reaction?
Part B: RATE of PRODUCT FORMATION
1. Select 100 toothpicks and place them in a shallow bowl.
2. In your group of 3, one person will be the timer, one will record the data, and the
third person will be the enzyme, toothpickase. The enzyme is to break the
toothpicks without looking and all of the products (“broken toothpicks”) must
remain on the plate.
3. The experiment is conducted in 20-second intervals. The timer calls out start and
then marks each 20-second interval. The recorder tallies the total number of
toothpicks broken as each interval is announced by the timer.
Data Table 1:
Time
20
(seconds)
Product
formation
(# of
Toothpicks
Broken)
40
60
80
100
120
140
160
180
Part C: REACTION RATE VS. TEMPERATURE
1. Select 10 toothpicks. Time how long it takes to break the 10 toothpicks as fast as
you can. (You can look.)
2. Place your hand in a pail of ice water for 2 minutes. This will get uncomfortable,
but stick with it.
3. Repeat step 1.
4. Compare the rate of enzyme action in toothpicks per second for room temperature
and for cold temperature. In the Analysis section, write up an explanation as to
what happened and why it happened.
Data Table 2:
Time to break 10 toothpicks at room temperature ________________
Time to break 10 toothpicks after ice water bath _________________
Part D: REACTION RATE VS. SUBSTRATE CONCENTRATION
1. Remove the broken toothpicks from the plate.
2. Place 100 paperclips in the bowl. The paper clips represent a “solvent” in which
the toothpicks are “dissolved”.
3. For the first trial, place 20 toothpicks on the plate with the paper clips. The
enzyme has 20 seconds to react (break as many toothpicks as possible). Record
the number broken at a concentration of 20. Remember, the “enzyme” cannot
look into the bowl.
4. Remove the broken toothpicks and repeat with concentrations of 30, 40, 50 etc. up
to 100 toothpicks.
Data Table 3:
Enzyme
Concentration
Product
Formation
20
30
40
50
60
70
80
90
100
Clean Up:
Put all broken toothpicks in the trash, and return unbroken toothpicks, paper clips and the
bowl to the front of the room.
Graph:
Obtain a piece of graph paper, graph data tables 1 on one side and 3 on the other side of
the graph paper. On both, graph the time interval on the x-axis and the product formation
on the y-axis. (These should be LINE Graphs.)
Conclusion:
Summarize what you did and describe your results. You must include the words
SUBSTRATE AND ENZYME in your conclusion. Make sure that you make specific
mention of information from your data tables and graphs.
Analysis/Extension: Answer the following questions using complete sentences.
1. Compare the cold conditions with the room temperature conditions. What did you
notice about how much product was formed?
2. Predict what would happen if 2 people were breaking toothpicks at the same time?
Why?
3. Predict what would happen if you added more toothpicks or altered the
temperature? Why?