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Effect of an enzyme concentration on the rate of reaction of gelatine.

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Effect of an enzyme concentration on the rate of reaction of gelatine. Aim The aim of the investigation is to find the effect of Trypsin concentration on the rate of digestion. This will be carried out on a gelatine substrate from photographic film. Background Enzymes have an active site which is shaped so that only a molecule, known as the substrate, with the correct shape can link into the enzyme. Once the enzyme and the substrate become associated, the enzyme can increase the probability of a chemical reaction occurring. As the substrate molecule comes into contact with the enzyme's active site it forms a temporary union with the enzyme. Thus, instead of a one-step reaction taking place, enzyme mediated reactions occur via an intermediate step in which the substrate first forms an enzyme-substrate complex which in turn undergoes a second reaction to form the final product and return the enzyme to its original status. By converting a one step reaction with a large activation energy into a 2-step process, each step of which has a smaller activation energy, the overall rate of product formation is increased. The specific action of an enzyme with a single substrate can be explained using a Lock and Key analogy. In this analogy, the lock is the enzyme and the key is the substrate. Only the correctly sized key (substrate) ...read more.


cm3 Table 2: The time taken for the different trypsin concentrations to digest the gelatine from the photographic film, carried out three times with same concentration. Trypsin Concentrations Time taken for digestion (min:s) 1 2 3 Start Finish Start Finish Start Finish 0.05% 2:00 27:04 2:30 27:28 3:00 28:00 0.1% 2:00 18:02 2:30 18:20 3:00 19:04 0.5% 2:00 9:07 2:30 9:40 3:00 10:02 1% 2:00 5:31 2:30 5:34 3:00 6:05 From the above raw data, the following calculations were carried out, to find out the length of time taken for digestion, the time in seconds, the rate of digestion per film, the average rate of digestion and the standard error in each set of experiments. For test tube 1 at 0.05% concentration, actual time = Finish - start = 27:04 - 02:00 = 25:04 This was repeated for each test tube for every concentration. The time in seconds for this test tube = (minutes * 60) + seconds = (25*60) + 04 = 1504 s All the times were converted to seconds for all concentrations. Rate of digestion for this test tube = 1 / time in seconds = 1 / 1504 = 6.65 x 10-4 s-1 Again rate was calculated for all the experiments. In each case the size of photographic film was kept constant, and therefore 1 has been used as the constant to calculate this rate of digestion per concentration. ...read more.


This led to the error bars shown in the graph for the 1% trypsin concentration, as this had the fastest rate of digestion. Methods for improving future investigations include timing the shaking of when the test tubes are taken out of the water bath so that the kinetic energy of the enzymes are not affected by the possible change in temperature. As this is nonetheless, supposed to be a constant in the investigation. Using a clear water bath would help with this, as there would be no need to take the test tubes out of the water bath. A second person to help start the stop clock would reduce errors in timing as vital seconds become unaccounted for when transferring the photographic film to the test tube and trying to start the stop clock at the same time. The tests could be carried out individually opposed to concurrently running them because checking for digestion lead to discrepancies in the time each test tube spent out of the water bath, which again affects the kinetic energy of the enzyme. The cuttings of photographic film with gelatine on could have been measured as larger pieces so that fewer errors occurred in trying to keep a constant size. In conclusion the time taken for digestion of the gelatine substrate was inversely proportional to the concentration of the trypsin enzyme, hence the rate of reaction increased as the enzyme concentration was raised. ?? ?? ?? ?? Biology Assignment 2 ...read more.

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