Factors Affecting Enzyme Activity
Group Members: Lydia, Tiffany, Megan, Omid
Explanatory: We hypothesize that extreme pH (very basic or very acidic) will cause enzyme activity (rate of reaction) to decrease.
Prediction: If pH is either too basic or too acidic, then the enzyme's reaction rate will decrease, because the enzyme will denature in those extreme conditions.
Null: The level of pH has no effect on the reaction rate of the enzyme.
Alternative: The level of pH has an effect on the reaction rate of the enzyme.
- LabQuest app
- Vernier Gas Pressure Sensor
- rubber-stopped assembly
- 10mL graduated cylinder
- 250mL beaker of water
- 3% H2O2 (hydrogen peroxide)
- enzyme suspension
- three 18 x 150mm test tubes
- pH buffers (pH 4, 7, 10)
- test tube rack
- three disposable pipettes
- Logger Pro
Dependent Variable: Pressure (rate of reaction)
- Amount of enzyme used
- Amount of substrate
- Amount of buffer
- Type of enzyme used
- Obtain and wear goggles.
- Connect the plastic tubing to the valve on the gas pressure sensor, and the gas pressure sensor to LabQuest.
- On LabQuest, change the data-collection rate to 0.5 samples/second and the collection length to 180 seconds.
- Place the three test tubes onto the rack and label them pH 4, pH 7, and pH 10.
- Add 3mL of 3% H202 (hydrogen peroxide) and 3mL of each pH buffer to each according test tube.
- In the tube labeled pH 4, add 2 drops of the enzyme solution.
- Stopper the test tube, and gently swirl to mix the contents. Connect the plastic tubing to the connector in the rubber stopper as quickly as possible, and then click the "Play" button to start data collection.
- Monitor the pressure readings on the device to make sure that it does not exceed 130 kPa. If that occurs, disconnect the plastic tubing from the gas pressure sensor because the pressure inside the test tube may cause the stopped to pop off.
- When data collection is done, disconnect the tubing from the stopper, remove the stopper from the test tube, and discard the contents into the sink.
- Determine the rate of enzyme activity for the pressure vs. time curve. Record the slope of the Linear Fit equation (trendline).
- Store the data of the run by tapping the File Cabinet icon, and make sure to label the runs according to the pH of the buffer used.
- Repeat Steps 6 - 11 for at least two more trials with the pH 4 buffer, and then for the test tubes labeled pH 7 and pH 10. Each pH condition should be tested in at least three trials in total.
Example poster layout created in Easel.ly
Factors Affecting Enzyme Activity Lab Handout