Enzyme Catalysis Lab
2H2O2
2H2O + O2
Problem: How does the reaction rate of an enzyme change when: 1) the enzyme concentration is doubled and the
substrate concentration is not changed 2) the substrate concentration is doubled and the enzyme concentrations is
not changed 3) the enzyme concentration is decreased by ½ and the substrate concentration is not changed 4) the
substrate concentration is decreased by ½ and the enzyme concentration is not changed.
Objective:
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
Observe the conversion of hydrogen peroxide to water and oxygen gas by the enzyme catalase.
Measure the amount of oxygen generated and calculate the rate of the enzyme-catalyzed reaction.
Materials:
-flask
-tubing
-glass dropper tube
-stopper
-100 ml. graduated cylinder
-calibrated medicine cups
-tub
-water
-potato enzyme solution
-Hydrogen Peroxide (H2O2)
Procedure:
PART 1:
1. In a medicine cup combine 10 ml of water and 10 ml of hydrogen peroxide
2. In a second medicine cup collect 10 ml of the enzyme solution (potato mixture).
3. Fill a container ¾ full of water and submerge a 100 ml. graduated cylinder in the water.
4. Place the rubber tubing into the submerged graduated cylinder and keeping the mouth of the graduated
cylinder under the water, invert the cylinder (make sure the cylinder is full of water-no air pockets at the top.)
5. Pour the hydrogen peroxide and catalase solutions into the flask, stopper and swirl the flask.
6. Begin timing when the first bubble of gas appears in the cylinder.
7. Collect the data in the chart.
PART 2:
1. Double enzyme (potato mixture)- collect 20 ml. of enzyme solution and repeat the experiment
2. ½ enzyme (potato mixture) – collect 10 ml. of enzyme solution and mix with 10 ml. of water and repeat the
experiment.
3. Double substrate (hydrogen peroxide) – collect 10 ml. of hydrogen peroxide ONLY NO WATER! And repeat the
experiment.
4. ½ substrate (hydrogen peroxide) – 20 ml of water and 10 ml of hydrogen peroxide and repeat the experiment
Hypothesis:
If…then…
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B._________________________________________________________________
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Null Hypothesis:
There is no significant difference between the original enzyme/substrate experiment and each of the
alternative enzyme/substrate experiments.
Data Table:
Experiment
Original
A – Double Enzyme
B – ½ Enzyme
C- Double Substrate
D – ½ Substrate
Enzyme
Hydrogen Peroxide
Original
Time
Amount of O2 Produced
Water
Double Enzyme
Time
Amount of O2 Produced
½ Enzyme
Time
Double Substrate
Time
Amount of O2 Produced
Amount of O2 Produced
½ Substrate
Time
Amount of O2 Produced
Line Graph: Include a title, label your x axis and y axis, make your lines 5 different colors!
Find the slope of each line at 3 different intervals. (Y2 – Y1 / X2 – X1)
Experiment
Original
Rate (ml/s)
Rate (ml/s)
Rate (ml/s)
Double Enzyme
½ Enzyme
Double Substrate
½ Substrate
Analysis & Conclusion:
Analyze your data and state whether your hypothesis is accepted or rejected.
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