Our cells make a poison called Hydrogen Peroxide (H₂O₂)... they don’t die from it because the enzyme “Catalase” inside our cells breaks H₂O₂ up into harmless molecules: water (H₂O) & oxygen (O₂).

H₂O₂ is the substrate that fits into the active site of the enzyme Catalase & undergoes a chemical reaction (in this case, digestion) catalyzed by the enzyme.

The Plan

See how the environment (temperature & acidity (pH)) affects Catalase's ability to work. If Catalase works well, chemical reactions occur; if it's damaged, reactions occur slowly, if at all. To tell which is the case:
- 1. see how much/fast a substrate (in our case, H₂O₂) disappears, OR
  2. see how much/fast a product (in our case, H₂O & O₂) appears.

We'll use the second approach & focus on one product, O₂: we’ll see bubbles if it appears.

Materials:

Where would we get Catalase? Catalase occurs in the cells of many tissues, e.g. your liver. We'll use catalase from beef liver. Can we see enzymes function in dead cells? Actually, yes: when a cell dies, its enzymes remain good for a few weeks, if the tissue is refrigerated.

Where would we get H₂O₂? The same Hydrogen Peroxide that our cells make (albeit diluted) occurs in... drugstores.

liver and peroxide.jpg

Your Task

Watch these 7 quick experiments testing Catalase function under different conditions:

Seven Quick Experiments

For each experiment, use this data sheet (or your own) to record:
- What was placed into the test tube & how much?
- Observed results.
- Interpretation: Did chemical reaction occur? Why/why not? (Indicate why it makes sense that a reaction did/didn’t occur, based on what is needed for enzyme-catalyzed reactions to occur. Hint: refer to the equation (top of page) to see what's needed for the reaction.)

Developed by Vasilissa Derugina.