In my investigation I will study the effect of enzyme concentration on the rate of catalyse activity.
Prediction
I predict that if I increase the enzyme concentration this will increase the rate of catalyse activity because there will be more active sites for reactions, resulting in more chemical reactions caused by successful collisions between the active site of the enzyme (catalyse) and the substrate (hydrogen peroxide)
(Gareth Williams, Biology For You pages 29-31)
Equipment
10cm3 measuring cylinder
Hydrogen Peroxide
Water bath
Pureed potato
Test tube
Delivery tube
Bung
Diagram
Plan
I will use the equipment as shown in the diagram to measure the amount of oxygen that gathers into the measuring cylinder. The amount of oxygen is directly related to the rate of catalyse activity. The more oxygen, the more catalyse activity and the less oxygen, the less catalyse activity. I will be able to measure the oxygen using the measuring cylinder.
I will be using pureed potato to provide the enzymes for this experiment. This is the best kind of potato to use because it has more surface area than whole potatoes and this means more active sites for the substrate to react with.I will be change the enzyme concentration(amount of pureed potato) in order to measure its effects on the rate of catalyse activity. I will perform the experiment using 0cm3, 1cm3, 2cm3, 3cm3, 4cm3, 5cm3 of pureed potato. In order to make it a fair test I must keep the volume the same for each test. The set volume will be 5cm3 so I will use water to keep the volume at 5cm3, this means that for example when I do the experiment with 3cm3 of pureed potato I will add 2cm3 of water. I will add 5cm3 of hydrogen peroxide each time in order to keep the test fair. I will use a measuring cylinder to measure out all these values. I will repeat the test at each value three times and then take an average to make it a fair test and I will also keep the temperature of the room the same throughout the experiment using the thermostatic controls in the laboratory. The temperature will remain at 20ºC.
These are the measurements I will be using.
TEST TUBE Enzyme(POTATO)(Cm3) WATER(Cm3) Substrate (Hydrogen peroxide)(Cm3) TOTAL VOLUME(Cm3)
1 0 5 5 10
2 1 4 5 10
3 2 3 5 10
4 3 2 5 10
5 4 1 5 10
6 5 0 4 10
Results
Test Tube Experiment No.1 Experiment No.2 Experiment No.3 Total Average
1 0 0 0 0 0
2 2.3 2.1 2.4 6.8 2.3
3 4.3 4.5 4.4 13.2 4.4
4 6.8 6.5 7.1 20.4 6.8
5 7.4 7.4 7.1 21.9 7.3
6 7.4 7.5 7.2 22.7 7.4
Conclusion
In conclusion I can see that my prediction was correct. The higher the enzyme concentration was, the more oxygen was produced. This is because the with higher enzyme concentration, there are more active sites where more successful collisions will take place between the active site of the enzyme and the substrate. The graph shows that as the enzyme concentration was increasing more and more, the rate of catalyse activity was increasing less an less which indicates that it was nearing the optimum rate of catalyse activity.
Evaluation
My experiment worked well although if I were to do it again I could do certain things differently in order to gain more accurate results. I would repeat the experiment more times as this would give me a more accurate average and I would also uses more different values in order to get a more detailed outlook on how enzyme concentration affects the rate of catalyse activity. I would also use a measuring syringe to measure the amount of oxygen because this is a much more accurate way of doing it.
