1. Michael Robbins
2/5/2014
Lesson: Enzymes
1) Major concept: Function of enzymes
2) Lesson essential question:
BIO.A.2.3.1: How do enzymes work a catalyst to regulate a specific biochemical reaction?
BIO.A.2.3.2: How do factors such as pH, temperature, and concentration levels can affect
enzyme function?
3) Key Vocabulary: Enzyme, Catalyst, Activation energy, Substrate, Enzyme substrate
complex (ES complex), Denaturation, pH, Inhibition, Allosteric enzyme, Competitive
inhibition, Allosteric site, Noncompetitive inhibition
4) Graphic Organizers Used
Worksheets to record predictions/observations
5) Activities
1. Activating Strategy: Funny Enzyme Cartoon
2. Enzymes Power Point
3. Enzymes Teacher Demonstration: Using Predict, observe and explain format.
4. Enzymes Song (YouTube)
Laboratory Demonstration (by Michael Robbins)
(Based on the elephant toothpaste reaction caused by the catalase enzyme.)
Materials, Equipment, and Set-Up:









8 250 mL Flasks
Rubber stopper
2 beakers for yeast and water mixture
3% Hydrogen peroxide
Dishwashing soap
Dry yeast
Distilled water
Food coloring
Paper towels

2. 
Balloons
Overview:
In this lesson, we will be demonstrating the breakdown of hydrogen peroxide to water and oxygen gas
known as elephant toothpaste. First, hydrogen peroxide, dish soap, and food dye are added to a flask.
Next, dry yeast is mixed in warm water for 30 seconds and then added to the flask. The hydration of
the yeast is necessary for the catalase enzyme to function. The catalase enzyme catalyzes the
breakdown of hydrogen peroxide to water and oxygen gas (2H2O2 2H2O + O2) and the dish soap
captures the oxygen molecules and foams up causing what looks like toothpaste being squeezed from
the top of the flask. The flask will heat up and the students will be able to touch the flask to feel this
effect. A deflated balloon will also be placed on top of another flask without the soap to show that
oxygen gas is being released (the balloon will inflate). We will run the experiment three times: once
with only hydrogen peroxide to show that the reaction by itself is very slow, again with the yeast added
where the reaction can be seen with soap (elephant toothpaste) and without (blowing up the balloon),
and a third time with boiled yeast (denatured enzyme) where the reaction will be too slow to be seen.
Students will be asked to make predictions before each experiment. The will use their knowledge of
the ingredients used in previous reactions and their previous observations to make educated
predictions.
Body of Lab: There will be three trials run in this lesson. Each trial will consist of predicting a specific
outcome, observing the experiment, and explaining why they saw what they saw for each trial.
Relevant Background Information
A) Student will be asked if they have ever out Hydrogen peroxide on a cut and what hydrogen
peroxide might be doing in this case.
B) Students will be told that hydrogen peroxide is a harmful product that is produced in their bodies
because of metabolism and that it must be converted to something less harmful.
C) The chemical equation for the catalase reaction will be given: (2H2O2 2H2O + O2). The students
will be told that the function of the catalase enzyme is to covert hydrogen peroxide in to harmless
water and oxygen gas.
D) I will then tell them that catalase is so important that many organisms need it including yeast
fungus.
E) I will tell students that the worksheet (placed on desks in front of them) will be used to write
prediction and explanations down for each experiment. I will perform the experiments in front of
them describing what I am going to do to allow the students to predict.
Prediction (1): I will show students two flask and tell them that hydrogen peroxide is in both flasks. I will
ask students to very briefly write down what they think will happen when balloons are placed on top of
one of the flasks. To make this activity more interesting, I will cover the flasks with rubber stoppers, to
make it appear that it is stopping the oxygen gas from escaping. Students should be asked to write down

3. and then share their predictions. Some might predict that the oxygen gas will cause the balloon to
expand, but some might predict that the balloon will not expand. The balloon will not expand because
the reaction that produces oxygen gas is very slow (No enzyme).
Observation (1): I will place a balloon over the flask. After a few seconds, I will ask the students what is
happening. They will reply that the balloon did not expand. Students should be asked to feel the flask. It
should feel normal as nothing special has taken place. In Observation 2 it will feel hot.
Explanation (1): After they observe this, I should ask: “Do you think the reaction by which H2O2 yields
water and oxygen gas is a very fast or a very slow reaction?” After student see that the balloon did not
inflate, most would correctly explain that the reaction to produce oxygen gas from H2O2 is very slow.
Relevant Background Information (2): I will add about a half a packet dry yeast to about 40 mL of water
and stir it for twenty seconds. While stirring they will tell students that mixing is done to activate an
enzyme contained inside the yeast. They will remind the students that the name of the enzyme is
catalase.
Prediction (2): I will ask students two questions:
A) “What do you think would happen to the balloon if the catalase enzyme is added to the first
flask from Prediction 1?”
B) “What do you think would happen if the catalse enzyme and a little soap are added to the
second flask from Prediction 1?”
Students should be asked write down their predictions. Students should be asked to share what they
think will happen. Given the clues some may correctly think that the catalase enyzme may detoxify the
hydrogen peroxide by converting it to water and oxygen gas. They may correctly predict that this will
cause the balloon to expand and the soap to make bubbles. They may alternatively incorrectly predict
that the hydrogen peroxide or soap will inhibit the enzyme and that nothing will happen. Both are
sensible predictions. (Optional: The prediction observation and explanation for experiment A above may
be completed before starting the predictions for experiment B.)
Observation (2): I will prepare the reactions of enzyme solution by mixing half a packet of yeast with
around 40 mL water. I will then pour the enzyme solution into the flasks containing 100 mL of 3%
hydrogen peroxide or 3% hydrogen peroxide with a little (~4 mL) dish washing soap and food coloring.
The students will observe the balloon inflating and the bubbles being formed from the soap. They
should be asked to touch the balloon and the flasks. Both should feel hot. The students can again feel
the cold flask from Observation #1 that does not have the enzyme and this will help students be sure
that the enzyme indeed caused a difference in temperature.
Explain (2): I should ask the students to explain and write their answers to the following:
A) “Why did the balloon inflate?”
B) “Why did the soap make bubbles?”
In this discussion we will talk about what the catalase enzyme accomplished?
The students should correctly infer that oxygen gas produced made the balloon inflate and the soap
bubble. Have a student that predicts correctly explain this to others that may not have come to this

4. conclusion. They should also be able to reason that, based on the first experiment, enzymes are needed
to speed up reactions otherwise they would move too slow and harmful substances will build up in cells.
Next, I will tell students that hydrogen peroxide carries a lot of chemical potential energy and is less
stable than water and oxygen gas and that’s why it ultimately is converted. I should then ask students if
anyone can guess: “Why were the flask and balloon hot?” (answer energy in the bonds of H202 was
released as heat)
Predict (3): Students will be shown two more flasks with hydrogen peroxide with and without the soap
added and will be told that the experiment will be repeated. This time the experiment will be done with
pre-boiled yeast. Tell the students that the flask was boiled and is still hot to touch. Some students may
predict that the heat will speed up the chemical reaction, however the key is that it was boiled so the
enzyme will not function.
Observe (3): Students will observe what seems like no reaction taking place. This is due to the enzyme
catalase in the yeast being denatured from boiling. This enzyme is the actual catalyst for the reaction.
Can anybody guess what boiling does to the enzyme solution?”
Explain (3): Students will be asked to write their explanations on the worksheet. Students will likely say
one of two things. 1. The enzyme is destroyed by boiling. This is correct. 2. The enzyme was killed. This is
incorrect. If this happens, ask the students if they think enzymes are alive or if they are type of chemical
found in living organisms. This leading question will help at least one student amongst the group to
come to the conclusion that enzymes are not alive and thus cannot be killed. Acceptable words to
describe the inactivity could be denatured, destroyed, or degraded.
Extension (3) (1 minute plus remainder of available time). Ask the students: “Why it is bad to have a
really high fever?” If needed rephrase the question and ask them: “What might happen to your enzymes
if your fever is too high?” Students should understand that human enzymes are sensitive to temperature
just like the yeast enzyme catalase was and if the temperature became too high enzymes would be
inhibited and people could get sick or die.