Name:
Date:
Score:_________/30 points
Enzyme Lab - CP
Introduction:
In chapter 2 section 4, 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 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 is present. You will also be using your saliva. There is an enzyme in
your mouth called amylase. Amylase is an enzyme that breaks starch down into sugar
(glucose) in your mouth before you swallow your food. Amylase is there to help speed up
the process of digestion.
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 down into sugar?
Hypothesis: (Write as an if/then statement that proposes an answer to the above
question) (1 point)
Procedure Part One: How exactly does amylase work?
1. Choose someone from the group (who is not sick) to spit in the disposable plastic
cup provided to you. This person should be the only person to handle the saliva. You
will use the plastic pipet with the saliva. Do not use any of the glass droppers.
2. Place 5 drops of the starch solution in the test tube labeled number one.
3. Place 5 drops of starch solution and 10 drops of saliva (containing amylase) into test
tube 2.
4. Place your thumb over the top of the tubes and gently mix the contents.
5. After 5 minutes place 3 drops of iodine in each tube, gently swirl.
6. Record results in the data table for part one. (5 points)
Data Table Part One: How exactly does amylase work?
Test Tube
Drops of
Starch
Drops of
Saliva
(amylase)
Initial Test
tube color
before
iodine
Final Test
End
Tube Color
Result
after adding (Starch or
iodine
Sugar in
tube)
1
2
Procedure Part Two: Effect of pH change on amylase activity (TEACHER DEMO)
1. Place 10 drops of hydrochloric acid (HCl) in the test tube marked pH1.
2. Place 10 drops of distilled water in the test tube marked pH 7.
3. Place 10 drops of sodium hydroxide (NaOH base) in the test tube marked pH 12.
4. Place 10 drops of saliva in each test tube. (Must quickly get to steps 4-6)
5. Place 5 drops of starch solution in test tubes marked pH 1, pH 7, and pH 12.
6. Stir gently by giving test tubes a gentle swirl.
7. Wait 5 minutes
8. Place 3 drops of iodine in each tube, gently swirl.
9. Record results in the data table for part two. (1 points)
Data Table Part Two: Effect of pH – YOU FILL IN END RESULT COLUMN
pH
Drops of
starch
Drops of
Saliva
(amylase)
Initial Test
tube color
before
iodine
1
5
10
Cloudy
7
5
10
Cloudy
12
5
10
Cloudy
Final Test
Tube
Color
after
adding
iodine
Black
Reddish
Brown
Black
End
Result
(Starch or
Sugar in
tube)
Procedure Part Three: Effect of temperature change on enzyme activity (TEACHER
DEMO)
1. Place 5 drops of starch solution in each test tube marked cold, warm, and hot.
2. Place 10 drops of saliva in each tube. (Must get the tubes to the teacher quickly after
adding saliva)
3. Gently swirl the contents by placing your thumb over the contents and 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. (1 point)
Data Table Part Three: Effect of Temperature – YOU FILL IN END RESULT COLUMN
Temperature
Drops of
Drops of
Initial Test
Final Test
End
starch
Saliva
tube color
Tube Color
Result
(amylase)
before
after adding (Starch or
iodine
iodine
Sugar in
tube)
Cold (8 C)
5
10
Cloudy
Black
Warm (37 C)
5
10
Cloudy
Hot (77 C)
5
10
Cloudy
Reddish
Brown
Black
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 enzyme activity? Use data to support your answer (2
points).
10. Why do changes in temperature affect 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)
Conclusion: ON LOOSELEAF: Restate your hypothesis. Do you accept or reject your
hypothesis? Use data to support your answer. (3 points)