 |
BIOLOGY CBL LAB - ENZYME CATALYSIS: CATALASE
|
Purpose: |
| To demonstrate the action of the enzyme catalase. Harmful hydrogen peroxide forms within many cells. The enzyme catalase catalyzes the breakdown of hydrogen peroxide according to the reaction shown below:
We will monitor the reaction by recording pressure changes as oxygen gas is given off during the reaction.
|
Materials: |
- CBL
- Erlenmeyer Flask
- Pipettes
- 1-holed rubber stopper to fit flask, fitted with glass tube
- TI-82/83 Calculator
- Pressure Sensor (PS-DIN)
- 1.5% solution of H2O2
- Catalase solution prepared from fresh calf’s liver or potato (must be kept on ice)
|
|
1. Preparation of Hydrogen Peroxide Solution (H2O2) |
- Hydrogen Peroxide can be purchased from the grocery store or pharmacy in a 3.0% concentration.
- Dilute it to 1.5% by adding an equal volume of distilled water. You will need 10 mL of H2O2 per laboratory set-up.
|
2. Preparation of Enzyme Solution (Catalase) |
A solution of catalase can be made from fresh calf's liver. Use the following procedure:
- Macerate a small 2 - 3 cm2 piece of fresh calf's liver in a beaker.
- Add 100 mL of ice cold distilled water and stir.
- Filter the mixture through cheesecloth. The color of the resulting filtrate should be light pink.
- An alternative source of catalase is raw white potato. Repeat the procedure above using similar size pieces of raw white potato.
|
3. Set-Up of Erlenmeyer Flask |
- Select an Erlenmeyer flask that can be stoppered snugly with a 1-holed rubber stopper. (A 125 mL flask is recommended, however, a 250 mL flask can be used. If the larger flask is used, the quantities of solutions will have to be doubled.)
- Insert the glass portion of an eyedropper (pipette) through the hole in the stopper so that the point of the dropper faces up. This set-up will permit the Tygon™ tubing of the CBL probe to fit onto the top of the eyedropper.
|
