Catalase serves to protect the cell from the toxic effects of hydrogen peroxide by catalyzing its decomposition into molecular oxygen and water without the production of free radicals (an atom or group of atoms with an unpaired electron, unusually reactive and are capable of causing a wide range of biological damage).
Hydrogen Peroxide (2H2O2) + Catalase = Oxygen + Water
METHOD:
EQUIPMENT LIST:
1x Water Bath
2x Boiling Tubes
1x Conical Flask
1x 5ml glass vial
1x Measuring cylinder
2x Beakers
1x Ice cream tub (containing water)
1x Stop clock
at least 100ml Hydrogen Peroxide
at least 50ml liquidized calf’s liver.
1x Retort stand
2x Boss and clamp
2x Thermometer
2x Pipette (5ml and 10 ml)
1x Safety Goggles
1x Bung and rubber tubing
VARIABLES:
I will do this by measuring the time taken for the water to reach the 10ml mark.
INTERVALS:
My experiment will be performed going up starting at 20o, then 40o, 60o, 80o, and 100oC.
SAFETY:
At all times there will be a teacher in the lab with me and I will be wearing safety goggles, as will everyone in the lab, at all times and will take extra precautions when handling hot water.
OBTAINING EVIDENCE
N.B for all the measurements of chemicals I have an error of 0.5ml.
TEST 1
TEST 2
TEST 3
AVERAGE
ANALYSING EVIDENCE AND DRAWING CONCLUSIONS
GRAPH:
ANALYSIS:
As you can see from my results from the graph, the amount of oxygen produced rises and then falls. This is because the optimum temperature is closest to 40oC so the reaction will be highest on that measurement. But as the temperature goes above that, the enzyme starts to get denatured and the reaction is not as large. When it gets to boiling point there is virtually no reaction at all. This is because as the temperature is raised, so is the energy level of the enzymes and substrate molecules. This causes them to have more kinetic energy thus collide more often causing a larger reaction. The enzyme starts to get denatured, however, because the molecules loose their bonds, which hold them into shape. The enzyme is denatured because it cannot form an enzyme substrate complex as its active site has been changed unalterably. Therefore my predictions were correct in that the reaction would decrease after 40oC.
EVALUATING EVIDENCE
Obviously my results are not 100% accuracy. This is because of slight human errors in of my experiment. Firstly the times were taken my human hand on a stop watch. I could have made it more accurate by using machine to find the exact time the level hit 10ml. But in the school labs they cannot provide us with such apparatus. Secondly the measurements of chemicals will not be exactly the same as what I have noted. There will be an error of about 0.5ml max. This is because yet again human hand is not completely accurate. Thirdly the temperatures may not have stayed the same when taken out the water bath, as the room temperature (about 20o) would have slightly cooled them down. This would only be possible to change if I performed the experiment in the water bath which would not give enough room for other people to work. Also the bung which I was using for the experiment may not have been completely air tight so some oxygen may have escaped but that should not make a vast difference on my results. I also could have taken more results for example go up in intervals of 5oC instead of 20. I also could have measured the amount of pure oxygen as other gases may have got in but yet again I don’t have the sufficient apparatus.
Overall I can say with confidence that my evidence is strong enough and accurate enough to support my conclusions as all the errors would only make a hardly noticeable difference to my results.
If I could make further investigation I might look at other variables such as concentration of the Hydrogen Peroxide. I also might go into researching other enzymes to compare the different reactions and temperatures in which the work.