Name:
Date:
Score:_________/40 points
Enzyme Lab
Introduction:
In chapter 2 sections 4 and 5, you learned about chemical reactions and how an
enzyme speeds up those chemical reactions that keep living things alive. An enzyme only
binds to and reacts with a specific substrate. Remember the reactants bind to the enzyme
at the active site. Reactant bonds are broken and reconfigured to make the product.
Enzymes are designed to speed up the reaction rates of these chemical reactions that
would otherwise be too slow to sustain life.
Check your understanding: What is the purpose of an enzyme? (1 point)
In this lab you will be working with a starch (amylose) solution. You will use a
chemical indicator called iodine. Iodine is used to test for starch. Iodine looks like a
brownish red in its normal state. When you drip iodine on starch it turns to a black/blue
color. This indicated that starch (amylose) is present. There is an enzyme in your mouth
called amylase. Amylase is an enzyme that breaks starch (amylose) down into sugar
(glucose) in your mouth before you swallow your food. Amylase is there to help speed up
the process of digestion. We will use a fungal amylase solution.
Check your understanding: If you drip iodine on a substance and it turns blue/black,
what does this mean is present? (1 point)
Check your understanding: What is the polymer in this scenario? What is the
monomer? What is the enzyme? (3 points)
In this lab you will be looking at three things. 1. How exactly does amylase work? 2.
How does pH affect the enzyme amylase. 3. How does temperature affect the enzyme
amylase.
*** You will be working with iodine which will stain your skin and
clothes, and acids and bases, safety equipment is necessary and you
must be very careful with all of these toxic liquids***
Problem: How does a change in pH and temperature affect how the enzyme amylase
breaks starch (amylose) down into sugar?
Hypothesis: (Write as an if/then statement that proposes an answer to the above
question) (1 point)
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Procedure Part One: How exactly does amylase work?
1. Place 5 drops of the starch/amylose solution in the test tube labeled number one.
2. Place 5 drops of starch/amylose solution and 10 drops of the amylase solution into
test tube 2.
3. Place your thumb over the top of the tubes and gently mix the contents.
4. After 5 minutes place 3 drops of iodine in each tube, gently swirl.
5. Record results in the data table for part one. (5 points)
Data Table Part One: How exactly does amylase work?
Test Tube
Drops of
Drops of
Initial Test
Starch/Amylose
amylase
tube color
before
iodine
Final Test
Tube Color
after
adding
iodine
End
Result
(Starch
or Sugar
in tube)
1
2
Procedure Part Two: Effect of pH change on amylase activity
1. Place 5 drops of starch solution in test tubes marked pH 1, pH 7, and pH 12.
2. Place 10 drops of the amylase solution in each test tube. (Must quickly get to steps
4-6)
3. Stir gently by placing thumb over test tubes and giving a gentle swirl.
4. Place 10 drops of hydrochloric acid (HCl) in the test tube marked pH1.
5. Place 10 drops of distilled water in the test tube marked pH 7.
6. Place 10 drops of sodium hydroxide (NaOH base) in the test tube marked pH 12.
7. Gently swirl again.
8. Wait 5 minutes
9. Place 3 drops of iodine in pH 1 and pH 7 test tubes. Put 12 drops of iodine in pH 12
test tube, gently swirl.
10. Record results in the data table for part two. (5 points)
Data Table Part Two: Effect of pH
pH
Drops of
Drops of
starch/amylose
amylase
1
7
12
Initial Test
tube color
before iodine
Final Test
Tube Color
after adding
iodine
End Result
(Starch or
Sugar in
tube)
Procedure Part Three: Effect of temperature change on enzyme activity
1. Place 5 drops of starch/amylose solution in each test tube marked cold, warm, and
hot.
2. Place 10 drops of amylase solution in each tube.
3. Gently swirl the contents by placing your thumb over the contents and swirling.
(Must get the tubes to the teacher quickly after swirling)
4. Ask your teacher to put a color-coded mark on your tubes before placing them in the
proper baths.
5. Place the cold test tube in the ice bath your teacher has prepared in the front of the
room.
6. Place the warm test tube in the warm water bath your teacher has prepared in the
front of the room.
7. Place the hot test tube in the boiling water bath your teacher has in the front of the
room.
8. Let tubes sit for 5 minutes.
9. Ask your teacher to remove the tubes for you after 5 minutes, be sure to come up
with your test tube rack.
10. Once back at your lab station, place 3 drops of iodine in each tube, and gently swirl.
11. Record your findings in the data table. (5 points)
Temperature
Drops of
starch
Drops of
amylase
Initial Test
tube color
before
iodine
Final Test
Tube Color
after adding
iodine
End
Result
(Starch or
Sugar in
tube)
Cold (8 C)
Warm (37 C)
Hot (77 C)
Analysis Questions:
1. What was the function of amylase in this lab? (1 point)
2. What was the substrate for amylase in this lab? What was it being broken down into? (2
points)
3. Was starch a reactant or a product in this reaction? (1 point)
4. Was sugar (glucose) a reactant or a product in this reaction? (1 point)
5. What is the function of enzymes like amylase in living things? (1 point)
6. How did pH change affect enzyme activity? Use data to support your answer (2 points).
7. Why do changes in pH affect enzyme activity? (1 point)
8. The typical pH of the human mouth is usually between 6.5 – 7.5. Does this make sense
with your results? Explain. (1 point)
9. How did temperature change affect/denature enzyme activity? Use data to support your
answer (2 points).
10. Why do changes in temperature affect/denature enzyme activity? (1 point)
11. The typical temperature of the human mouth is 98.6°F (37°C). Does this make sense
with your results? Explain. (1 point)
12. What do you think would happen if I increased the enzyme concentration (instead of a
1% amylase concentration, what if we used a 20% amylase concentration) what would
happen to the reaction rate? (1pt)
13. What if I kept the concentration of amylase the same, but I increased the concentration
of starch/amylose? How would that change the reaction rate? (1pt)
Conclusion: (On loose-leaf) Restate your hypothesis. Do you accept or reject your
hypothesis? Use data to support your answer. Please discuss reactants, products, enzyme
activity, normal enzyme conditions, and how an enzyme can be denatured. (3 points)