The Effect Of Substrate Concentration On The Activity Of The Enzyme Catalase
A Level Biology Project
This is an experiment to examine how the concentration of the substrate hydrogen peroxide affects the rate of reaction of the enzyme catalase.
This is a real A-level school project and as such is intended for educational or research purposes only. Extracts of this project must not be included in any projects that you submit for marking. Doing this could lead to being disqualified from all the subjects that you are taking. You have been warned. If you want more help with doing your biology practicals then have a look at 'Advanced Level Practical Work for Biology' by Sally Morgan. If you want more detailed biology information then I'd recommend the book 'Advanced Biology' by M. Kent.
Enzymes such as Catalase are protein molecules which are found in living cells. They are used to speed up specific reactions in the cells. They are all very specific as each enzyme just performs one particular reaction.
Catalase is an enzyme found in food such as potato and liver. It is used for removing Hydrogen Peroxide from the cells. Hydrogen Peroxide is the poisonous by-product of metabolism. Catalase speeds up the decomposition of Hydrogen Peroxide into water and oxygen as shown in the equations below.
Hydrogen Peroxide---------------------->Water + Oxygen
It is able to speed up the decomposition of Hydrogen Peroxide because the shape of it's active site matches the shape of the Hydrogen Peroxide molecule. This type of reaction where a molecule is broken down into smaller pieces is called an anabolic reaction.
Apparatus Needed For The Experiments
Test Tube Rack
To test out how the concentration of hydrogen peroxide affects the rate of reaction first set up the apparatus below.
[Aparatus picture not reproduced]
1. Add 2cm3 of yeast to one test tube. Add 4cm3 of hydrogen peroxide solution at a concentration of 20% to the other test tube. Use a pipette to measure out the volumes. It is very important to accurately measure the amounts of Hydrogen Peroxide, Yeast and water to ensure a fair test.
2. Pour the hydrogen peroxide solution into the test tube containing the yeast and immediately put the gas syringe bung on the end of the test tube, at the same time start the stopwatch.
3. Bubbles should start to rise up the tube and the gas syringe will move outwards, as soon as the gas syringe passes the 30cm3 mark stop the stopwatch and note the elapsed time down to the nearest 1/10th of a second.