Name:

Date:

Period:

Title: The Toothpickase Lab

Purpose/Background: Organisms on every level, from elephants and blue whales down to amoebas and lowly bacteria, can be described as being simply bags of chemical reactions. If left on their own, most of these reactions would either not happen at all, or happen too slowly. Just as matches won’t light on their own, these reactions need to be helped along so they can be controlled.

Biologists are very interested in enzymes – protein catalysts that control many of the reactions that occur in living organisms. Enzymes are used in all metabolic reactions to control the rate of reactions and decrease the amount of activation energy necessary for the reaction to take place.

Enzymes are specific for each reaction and are reusable. Enzymes have an area called the active site to which a specific substrate will bond temporarily while the reaction is taking place.

In this activity, you will actually become an enzyme and cause a reaction to take place. One member of the group will be the timer. The toothpicks are the substrate. The other student, or students, in the group represent enzyme molecules. When you break a toothpick, the place where the toothpick fits between your fingers is the active site of the enzyme.

Hypothesesis: If the temperature is decreased, then the reaction rate will ______.

Procedures:

  1. Count out three piles of 40, 80, and 120 toothpicks on your desk.
  2. From the first pile, break as many toothpicks as you can in 10 seconds and record this on the data table. Broken toothpicks should be thrown into the pile of unbroken toothpicks because products and reactants mix in metabolic reactions. Do not break toothpicks already broken.
  3. Use the second pile to do another 20 seconds of breaking and count and record the number of toothpicks broken in the second period of time.
  4. Do 30 seconds of more breaking using the third pile and count and record the number of toothpicks broken.

Data (room temp):

Time (seconds) / # of toothpicks broken / Enzyme rate (# of toothpicks divided by time)
10
20
30
  1. Calculate the enzyme reaction rate by dividing the number of toothpicks broken by the time elapsed.
  2. Graph the number of toothpicks broken as a function of time (10, 20, and 30 seconds). Be sure to title your graph and label the x and y-axis.
  3. Repeat steps one through 4 above, only this time have the student(s) that break(s) the toothpicks soak their hand in ice water for 45 seconds before breaking any toothpicks.
  4. Make another data table and add these results to your original graph:

Data (colder temp):

Time (seconds) / # of toothpicks broken / Enzyme rate
10
20
30

Questions/Analysis:

  1. Draw a picture of a hand and a toothpick. Label the parts that represent the enzyme, substrate, and active site in this simulation.
  2. What would happen to the reaction rate if the toothpicks were spread out so that the breaker had to reach for them? Explain.
  3. What should happen to the reaction rate if more toothpicks (substrate) were added? Explain.
  4. What would happen if the breaker wears bulky gloves when picking up toothpicks? What does wearing the gloves represent?
  5. What if the enzyme was put into boiling water for one minute? Would the reaction rate return to normal after the active site cooled down? Why is this different than putting the enzyme in ice water? (Hint: think about the bonds)
  6. Which causes a more permanent change in the enzyme, cooling or heating?

Conclusion: Restate your hypothesis. Was it supported or not? Explain. What factors affect the function of enzymes?