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Investigating the rate of an enzyme controlled reaction.

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Investigating the rate of an enzyme controlled reaction Plan Enzymes- are biological catalysts. They speed up the chemical reactions that go on inside living things. Enzymes are made inside cells. Once formed, the enzyme may leave the cell and do its job outside. These enzymes are called extra-cellular enzymes and these include the digestive enzymes which breakdown food substances in our gut. Other enzymes do their job inside the cells. These are called intra-cellular enzymes. The properties of an enzyme * They are always proteins This is one reason why we need protein in our food * They are specific in their action Each enzyme controls one particular reaction or type of reaction * They can be used over again This is because they are not affected by the reaction * They are destroyed by heat This is because all proteins are denatured after about 45oc * They are sensitive to pH Most enzymes work best at neutral conditions A diagram to show how enzymes work Substrate fits Reaction takes place Product leaves into active site active site I have chosen to investigate the rate in which the enzyme-controlled reaction takes place. ...read more.


If the enzyme gets too hot, it will change shape (become denatured). It will no longer fit together with the starch and this will slow the reaction down. Human enzymes work best at body temperature (37oc) so I expect that the fastest Starch break down will occur will be at around 40oc. Method Equipment used * White tile * Iodine * Amylase * Starch * Test tube x2 * Stopwatch * Thermometer * Beaker x2 * Pipette * Measuring cylinder x2 1. 10 cm3 of Starch is measured out into a test tube using a measuring cylinder and 1 cm3 of Amylase is put into a separate test tube. 2. The two test tubes are then placed into a beaker of water and heated to the desired temperature. This is checked with a thermometer. 3. When the temperature is right the iodine is then dropped into rows of four onto a white tile. The Starch and enzyme are then poured into the same test tube. At this point the stopwatch is started as the two solutions mix. ...read more.


At 60oc the reaction was slower because the enzyme had become too hot and started to denature. Enzymes are made of protein and are very sensitive to high temperatures. Evaluation My results are probably not very accurate. I know this because the repeats for each temperature show a large variation for example at 35oc, the temperatures range from 229 and 191. One reason for this could be that the colour change is quite hard to follow by eye and it is difficult to see exactly when the experiment has finished. Although my results are not very reliable, they are good enough to show a trend. This is shown on the graph. There is one anomalous result at 40oc, the mean average time was 217 (s) which is higher than at 35oc. This is probably because it was difficult to be accurate about the colour change. If I did the experiment again I would make it more accurate by doing more repeats and use a wider range of temperatures because this would give a more accurate mean average. ...read more.

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