Exploring Enzyme Reaction Rates
Toothpickase Activity
Objectives:
1)To experience how a enzyme works by becoming an enzyme, toothpickase, which
breaks toothpicks at timed intervals.
2)Calculate how many toothpicks are broken per second to determine the rate of reaction for the enzyme toothpickase.
3) Determine the affect of temperature of enzymes.
Discussion:
The vocabulary of an enzyme reaction will be modeled with hands and toothpicks.
The enzyme will be a student's hands with a particular shape (actually
demonstrates a quaternary structure with the two sub units coming together). The
active site is the portion of the thumbs and index finger which form a
space with which the toothpick fits. The substrate is the toothpick,
which can be broken into two products.
The rate of reaction can be measure by counting the amount of product produced or by counting the amount of substrate remaining. There are many factors that affect the rate of an enzyme reaction. Break a toothpick. Can a toothpick be broken faster? Can it be broken infinitely faster? Given a pile of toothpicks (substrate) and ideal conditions, it still takes some time for the enzyme to break the toothpick... that is the enzyme's V-max. If the room were filled with toothpicks, the rate would not increase, at least not initialing.
Part 1 Procedure:
1)Each student take 40 toothpicks.
2)Have groups break for time intervals: 0 sec, 10sec, 30sec, 60 sec, 120 sec 180
sec.
3)Record number of toothpicks broken (metabolized) during each time interval in
data table.
4)Graph the data
5) Calculate the average rate of reaction at each of the time intervals using
the formula for slope m2-m1/t2-t1
Results:
| Time (seconds) | Average Toothpicks Metabolized |
| 0 | |
| 10 | |
| 30 | |
| 60 | |
| 120 | |
| 180 |
Part 2 Procedure:
1)Each student take 40 toothpicks.
2)Have students choose ice water, room temp water or warm water to put their
hands in for 1 minutes and record temperature of water.
3)Record number of toothpicks broken (metabolized) during a 60 second time interval
for each temperature in
data table.
4)Graph the data
Results:
| Temperature (◦C) | Average Toothpicks Metabolized |
Analysis Questions:
1) What were some observations that you made during the two activities? How would they
relate to enzymes?
2) What happens to the reaction rate in part 1 as time goes on?
3) Would it take longer to break the toothpick if it was across the room on the floor (lower substrate concentration)?
4) If it was surrounded by look-alikes (competitive inhibitors)?
5) What would happen to the amount of time to break toothpicks if two or more people were breaking at the same time (enzyme concentration)?
6) What would happen if one half gets thrown up in air (gas product) other half is dropped back into the pile (liquid or solid product)?
7) What would happen if we continued to heat the water until it burnt your hand (denatured enzyme due to high temperature)?
8) What would happen if we rubber banded/taped our finger and thumb together (denatured enzyme due to pH)?