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 and the first finger of each 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 two hands ONLY.

3. You must break each toothpick completely in half.

4. You cannot begin before the teacher calls Go!

5. You must stop precisely when teacher says STOP!

Part A: RATE of PRODUCT FORMATION

  1. Select a pile of approximately 250 toothpicks.
  2. Divide them into four piles of 40 toothpicks each, with a few left over.
  3. Obtain a few „competitive inhibitors“ (twist ties).

4. Break the toothpicks for six selected time intervals:

30 sec., 60 sec., 120 sec., and 180 secs

5. Record your results in the attached data table noting time and toothpicks

metabolized. (Data Table #1).

6. Graph the results plotting Product Formed (the total number of toothpicks broken) vs. Time (30s, 60s, 120s, 180s...). Do not forget to title your graph.

Part B: REACTION RATE VS. TEMPERATURE

  1. The teacher will select a couple of students to stick their hands in ice before performing this activity. They will then follow the same procedure in Part A.
  2. Record the results in Data Table 2.

Data: Table 1: Rate of Product Formation

Time Interval / Product Formation (How Many Toothpicks Broken) / Class Average
30 s
60 s
120 s
180 s

Data: Table 2: Rate of Product Formation in Cold Temps

Time Interval / Product Formation (How Many Toothpicks Broken) / Class Average
30 s
60 s
120 s
180 s

Graph: Time intervals on x axis, Product Formation on y axis. Use your data. There will be 2 lines on your graph, one for Regular temperatures and one for cold temperatures. Please label each.

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) What did your fingers represent? What did the toothpicks represent?

2) Compare the cold conditions with the room temperature conditions. What did you notice about how much product was formed?

3) Predict what would happen if 2 people were breaking toothpicks at the same time? Why?

4) Predict what would happen if you added more toothpicks, altered the pH, or altered the temperature? Why?

5) Propose an experiment to test the addition of toothpicks to the experiment. What would you expect to find in your data?