Experiment: catalytic reactions in biology

Here, we provide instructions for an experiment that detects the biochemical activity of catalase peroxidase.

To understand the important principles behind this step, it is not essential to do this experiment at this stage or, in fact, at all. If you are not able to carry out this experiment, read through the details below and try to work out what you would expect to see. You could set up a discussion about your expectation using the Comments boxes.

If you are studying this course with other people (e.g. within a school class), you might want to think about doing the experiment together

If you do plan to carry out this experiment, you will need to read the instructions carefully and do some planning before starting it.

Materials required

For this experiment you will need:

• A potato
• Yeast (dried or fresh)
• Hydrogen peroxide (available at different concentrations – max 40% – at pharmacies)
• A small amount of water
• A few drops of washing-up liquid
• A glass, jar, yoghurt pot or other container
• Safety spectacles

Please be aware that hydrogen peroxide is a bleach and will discolour any material it comes into contact with (even your hands). While it is always a good idea to wear safety spectacles when doing chemistry this is one experiment, depending on how it is carried out, where it is highly advisable.

Experiment to detect the activity of catalase peroxidase

Mix the yeast and water and leave it to stand for 5 – 10 minutes. There should be enough water that the mixture pours easily. While you are waiting cut a fresh piece of potato. Put some hydrogen peroxide solution in a container and add the freshly cut piece of potato. What do you observe?

Put some more hydrogen peroxide into another container and add a few drops of washing-up liquid. The enzymes in the yeast should turn the hydrogen peroxide into water and oxygen. As oxygen is a gas the washing up liquid will make a foam that captures the bubbles of the gas, making it easier to see what is happening. Add the yeast to the mixture of hydrogen peroxide and washing up liquid and observe what happens.

If you have the opportunity to conduct this experiment, feel free to post comments about what you observe.