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Investigating the rate of reaction of enzymes in the clearing of photographic film.

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Investigating the rate of reaction of enzymes in the clearing of photographic film What are enzymes and what do they do? Enzymes are proteins that speed up the rate of reaction in living things without being changed themselves. They are composed of polymers of amino acids and are biological catalysts. They speed up reactions by a process called the induced fit hypothesis. Originally it was believed that the 'lock and key' hypothesis was how the enzymes work, but this is now believed to be incorrect because the enzymes can change shape so that the substrate (the thing that is broken up) can fit into the active site of the enzyme, which is why it is called the induced fit hypothesis. The lock and key hypothesis suggests that the enzymes are the correct shapes without having to change for the substrate to fit in, which they often are not. The substrate enters the enzyme and is digested in the active site of the enzyme. Aims of my investigation In the investigation I am going to study one of the four factors that alter the rate of reaction of trypsin in the clearing of photographic film. ...read more.


6) Repeat each result at least once so that an accurate average can be obtained. Repeat any anomalous results. Fair Test The experiment must be a fair test or I will be getting a lot of anomalous results and there may not be a clear pattern in the results. To make the experiment a fair test I am going to make sure that volumes of trypsin and pH buffer are the same in each experiment and the size of the photographic film is the same. I must also make sure that the temperature of the water and the trypsin and pH buffer remains at 40�C to keep the experiment accurate. I will also need to make sure that the photographic film is completely clear before I stop the timer. When I think it is clear I will press the red button on the timer and if the film goes no clearer I will take the time that I paused the timer at. If it does go clearer I will continue the timer and stop it when it goes clearer. Safe Test As well as the experiment needing to be a fair test, it must also be a safe test for it to be successful. ...read more.


This will be a problem unless another way of is found to stop the clock. One way which would make the stopping of the clock at the right time would be to use a light on one side of the test tube and a light sensor on the other side of the tube connected to a stopcock. When the light sensor detects light through the acetate when it is clear, it would stop the clock. This would eliminate the problem of human error in stopping the clock at an incorrect time. Although there will be slight inaccuracies in my results, the basic shape of the graph is definitely quite clear. The graph shows that as the pH increases from 5 to 7 the rate of reaction increases and as the pH increases from 7 to ten the rate of reaction decreases. I could make my results even more clear by using more pH values, I could use from 3 to 12, and some of which are not available in school. I could try mixing an even quantity of two consecutive pH values to gain a midway pH value. This would give me much more accurate results and any anomalous results would become much clearer and I could re-do them and hopefully gain a more accurate result. ...read more.

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