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How environmental factors affect the rate of an enzyme catalysed reaction.

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Biology coursework Aim:- To find out how environmental factors affect the rate of an enzyme catalysed reaction. In this experiment the factor which will be varied is temperature. The enzyme used will be amylase. Amylase's substrate is starch, which is changed to maltose. Plan:- In this experiment I am going to heat equal five quantities of amylase and equal five quantities of starch to different temperatures. The corresponding temperatures of starch and amylase will be mixed and kept at that particular temperature. The solutions will be tested at regular intervals for starch, using the iodine test. Sugar will then be tested for in each of these solutions at the end. Method:- In five separate boiling tubes, 2cm3 of 1% amylase was added. Each of these boiling tubes were put in to a water bath set to different temperatures, 0oC, 25oC, 45oC, 65oC, 85oC, these were left for five minutes to adapt to the temperature. This was be repeated for 8cm3 of 1% starch. After five minutes the starch and amylase of corresponding temperatures was mixed in a boiling tube and placed back in to the water bath (of a matching temperature). ...read more.


As the temperature decreases I expect the rate of the enzyme reaction to decrease. As the temperature increases, above 37oC, I expect the rate of enzyme reaction to decrease. Explanation of prediction:- I believe that I will find the above results due to my scientific knowledge. Protein has a particular shape, enzymes, therefore, have a particular shape, seeing as they are proteins. Enzymes can only work by colliding with complementary substrates. The active site of an enzyme molecule has a distinctive composition in to which specific substrate molecules will fit. The shape and position of chemical groups in it certify only the substrate molecules with the complementary shape and structure will combine with the enzyme. As the temperature of the amylase and starch solution increases the movement of enzymes increases, therefore, increasing the frequency of collisions, hence the enzyme reaction rate increases. As the temperature decreases the movement of enzymes decreases, hence the frequency of collisions is decreased and the enzyme reaction rate decreases. It is proven that amylase works most efficiently at approximately 37oC, this is because the enzyme is specifically used in the body, which holds this approximate temperature constantly. ...read more.


These factors will be kept constant in order to insure the experiment is carried out in a way which the affect of temperature, rather than anything else (like concentration), can be monitored on the rate of an enzyme catalysed reaction. For this to be a completely fair test there should be a 'control', unfortunately this is impossible as the appropriate control would be a solution kept in an atmosphere with no temperature, as this is impossible the best control is a solution which contains no enzyme, this would be to prove that temperature alone does not break down starch. Due to lack of time the results for this control will be taken from a previous experiment, the model gut experiment. Prelimary work:- Work which has been done at previous times on enzymes include the model gut experiment and the action of lipase. These experiments aided me to make predictions because of previous results. The experiment done on the action of lipase showed that without an enzyme (lipase) the substrate (fat) was not broken down. The concentrations and volumes used were decided from the previous model gut experiment. 1 ...read more.

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