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To investigate the effect of pH on the activity of the enzyme Trypsin

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To investigate the effect of pH on the activity of the enzyme Trypsin Aim To investigate the effect of pH on the activity of the enzyme Trypsin using a range of buffer solutions and exposed photographic negative. Hypothesis Trypsin will have an optimum pH (the rate of reaction will be highest at that pH) and the rate of reaction will decrease below and above the optimum pH. Apparatus 3% trypsin solution Buffer solutions at pHs 3,5,7,9 and 10 5 pieces of exposed photographic negative (1.5cm2) 5 pieces of wire (about 15cm long) 5 test tubes 2 10cm3 graduated pipettes 2 Pipette fillers 1 thermostatically controlled water bath 1 thermometer 1 stop clock Method The 5 pieces of exposed photographic negative were put onto the ends of the 5 pieces of wire. 5cm3 of trypsin solution was put in to a test tube. 2cm3 of buffer solution at pH 7 was added to the test tube. The test tube was put into the water bath (set at 25?C) ...read more.


(Seconds) (s-1) 3 21mins 49s no change ?? 0.00 5 5mins 34s 334 2.99 7 2mins 2s 122 8.20 9 1min 49s 109 9.17 10 1min 2s 62 16.13 ??assuming that the enzyme (trypsin) will not work on the substrate (gelatine) after any amount of time. Discussion The reading at pH 10 seemed inconsistent with the rest of the results, the rate of reaction seemed to be flattening out between pH 7 and 9 and then it increased quite a lot between pH 9 and 10. So it is thought that the reading at pH 10 was an anomalous result. It would have been a good idea to repeat the measurement at pH10 but there was not enough time in the lesson to repeat it. If the anomalous reading at pH 10 is ignored it was found that as the pH increased the rate of reaction increased and then began to flatten out (increase less). It would be expected that if the measurement for pH 10 was repeated and more measurements were carried out for pHs higher than 10 then it would reach an optimum pH (the rate of reaction would be highest at that pH) ...read more.


Which is not good as living organisms need enzymes. Reasons that might effect the accuracy or reliability of the results are: * The pieces of negative were not exactly the same size so the slightly bigger pieces would take a little longer to become clear. * The amount of trypsin and buffer solution measured and put into the test tube was not very exact. To improve this the amount of trypsin and buffer solution could be measured more precisely. * The temperature of the water in the water bath may have been slightly different for different pHs. So for example if it was slightly hotter it would increase the rate of reaction a little. The method could be improved by doing the experiment twice at the different pHs to check that the 2 results at a pH are about the same. This would make sure that the results are correct. Also if more measurements were taken at pH's 10 and above it could be found out what the optimum pH was and when the rate of reaction started to decrease, because of some of the enzymes being denatured. ...read more.

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