Enzymatic Activity and Inhibitors

Names: Biology Per: __

Enzymatic Activity and Inhibitors:

Background Discussion

Enzyme: ______

Substrate: ______

Catalyst: ______

Reaction Inhibitor: ______

When you eat something and it needs to be broken down, enzymes are the agents that act like catalysts to do this. Enzymes speed the rate of a reaction without being changed themselves. But how can we measure the rate of reaction of an enzyme? Also, is the rate of reaction the same for the entire time that the enzymes and the substrate (the food you eat) are together? This is the purpose of this lab.

Purpose:

Determining the reaction time of enzymes using common materials as our example. Also, determining the rates of these reactions with inhibitors in the substrate. Using their enzymes (hands), students will break down substrates (toothpicks) and the rate will be recorded, logged, and graphed to show reaction times.

Materials:

Wooden (Flat) Toothpicks. Plastic Cups

Colored toothpicks Watch with second hand

Procedures:

Decide responsibilities for each of the three partners in your group. The responsibilities are the following 1. Then Enzyme, 2. The timer/recorder, and 3. The counter. These responsibilities may change before you start, or between trials, but not during the trials.
One person will obtain the plastic cup and +/- 100 toothpicks. Lay them out on your table, or desk and count out 50 of the toothpicks and put them into the cup.

READ #3 THROUGH #7 BEFORE YOU BEGIN THE FIRST TRIAL SO THAT YOU HAVE AN IDEA OF WHAT YOU WILL BE DOING.

When told to begin by the timer, the person who is the enzyme will begin to take toothpicks out of the cup (reaction area) and break them ONE AT A TIME AND RETURN THE BROKEN PIECES TO THE CUP. This breaking of toothpicks is an Enzymatic Reaction. The counter will count how many toothpicks the enzyme breaks and puts back into the cup and call out the count so that the timer/recorder will hear the count at specified times.
The timer will record the count called by the counter at every 10 second mark on the data table following the procedures of this lab and continue the recording of the count at every 10 second intervals for one minute and 30 seconds or until the enzyme has broken down all substrate.

Example of Data Table Entries

Time (sec.) / Reactions
0
10 sec. / 9
20 sec. / 15
30 sec. / 19
40 sec / 24
50 sec / 29
1.0 min / 31
1 min 10 sec. / 32
1 min 20 sec. / 35
1 min 30 sec. / 36

The enzyme will continue to break the toothpicks one at a time without stopping until they have broken all the toothpicks, or until they have reached three minutes.
The enzyme MAY NOT remove broken toothpicks from the cup or break an already broken toothpick. Any toothpick that has already been broken the is picked up must be put back into the cup.
Before you begin “TRIAL #1”, write your prediction as to what you think will be affects of the experiment on the reaction times between intervals. Make sure to write your hypothesis in correct form. Proceed with Trial #1.
Now that you have finished with the trial, answer the question in the data section of the lab and graph your results on the graph provided. Throw away the toothpicks from Trial #1.

Proceed to Trial #2

You will repeat steps 1 and 2 in the procedures except you will obtain and add 25 colored toothpicks to the cup.
Repeat steps 3 through 7. It is not imperative to use the same roles for this trial, so if you want to have another person be the enzyme, it would be OK. Whoever is the enzyme must not try to break the colored toothpicks. They must be put back into the cup whole, and not be removed.
Make sure to record what you believe your hypothesis will be for the trial with the added feature of colored toothpicks in the substrate. Save the colored toothpicks and throw away the flat toothpicks.

Data Section:

Trial #1

Hypothesis: (what do you think will happen within the 1.30 time frame?)

Data Table:

Time (sec.) / Reactions
0 / 0
10 sec. / 9
20 sec. / 15
30 sec. / 19
40 sec. / 24
50 sec. / 29
1 min / 31
1 min 10 sec. / 32
1 min 20 sec. / 34
1 min. 30 sec. / 36

Graph:

Y axis

Dependent

50------
-----
25------
------

0 10 20 30 40 50 1.00 1.10 1.20 1.30

X axis Independent

Questions Trail #1

Did you break down all the substrate?______
Was there a difference in the amount of the substrate that the enzyme could break over the time intervals of the trial?______. If so, what would have caused the differences?

If there were a huge number of substrate molecules, would it have made it easier for the enzyme to do its job? Why?

Trial # 2

Hypothesis: (what do you think will happen with an inhibitor given the same time frame?)