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Biology Coursework - Enzymes.

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Introduction

Biology Coursework - Enzymes. Aim: To investigate the effect of temperature on the enzyme catalase. Prediction: I think that at 40�c, the catalase will produce the most oxygen, and at 20�c (the lowest temperature) and 80�c (the highest temperature) the catalase will produce the least amount of oxygen. Hypothesis: An enzyme is a catalyst; a chemical that speeds up a reaction while remaining unchanged itself. This allows the enzyme to be used repeatedly. If not for enzymes, these chemical reaction would still occur, but at such a slow rate that the organism would die. The substances that the enzyme works on is known as the substrate, and the reaction itself takes places on the part of the surface of the enzyme known as the active site. Each type of enzyme is specified to work on a certain type of substrate. This can be known as the lock and key mechanism. It can be described as so as one type of substrate can only 'fit' into one type of enzyme, before it is either built or broken as needs require, and then released. Enzymes can be split into two categories: builders and breakers. Enzymes work by reducing the amount of activation energy required. ...read more.

Middle

These should be measured with a measuring cylinder. Leave the test-tubes in the appropriate temperature - if you are performing 20�c, then leave it in room temperature. If you are performing 40�c, then leave them all in a water-bath set at 40�c. Leave them in there till they have reached the appropriate temperature. Step 3: Set up the rest of the apparatus to collect the amount of oxygen released. It should be set up as below: Step 4: Take one test-tube of liver solution, and another of hydrogen peroxide. Pour the hydrogen peroxide into the liver solution, quickly put the delivery tube on the test-tube and start timing. You need at least 2 people to perform this. Time for about 5 seconds, and then measure the amount of oxygen released into the measuring cylinder. Record this result. Step 5: Repeat for other experiments. Fair Test: * The same dilution of liver solution should be used throughout, so there are not different concentrations of hydrogen peroxide. * The same equipment should also be used throughout the experiment i.e. same water-baths, same stop-watch. Measuring cylinders and pipettes should also only be used for one type of solution; the hydrogen peroxide or liver solution. * The experiment should be performed 3 times for each temperature, and then an average calculated from those results to obtain more accuracy. ...read more.

Conclusion

If they weren't, that would also have contributed to the experiment. Despite all these errors and flaws, other attempts managed to be successful enough to balance out those anomalous results, so our end results turned out as we expected. We were able to draw the conclusion that enzymes are affected by heat as they gain more kinetic energy, up to a point (which was 40�c), after which they started to denature, therefore decreasing the rate of reaction at which the enzymes worked. If I was to perform this experiment again, I would have made more liver solution, to make room for error as well as to allow for some practises, to develop technique. I would also have the appropriate amount of apparatus, which would solve the problem of excess water in the test-tubes, and it would also save time so more liver solution could be used while it was all the same concentration (no solute left at the bottom). I would also be sure to take the temperature of the liver solution and hydrogen peroxide, to make sure it was at the correct temperature. To extend this experiment, I would go on to find out how other factors affect the rate of enzymes, for example, the actual concentration of the substrate, or the concentration of enzymes. Rachel Dennis ...read more.

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