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To investigate the effect of temperature on the breakdown of starch by amylase, and to find the optimum temperature for the reaction.

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Introduction

Aim: To investigate the effect of temperature on the breakdown of starch by amylase, and to find the optimum temperature for the reaction. Research: Enzymes are proteins that control vital biological processes. They often act as biological catalysts. They are made in cells. A catalyst is a chemical substance which speeds up a reaction but does not get used up during it. One enzyme molecule may be used several times over. If starch is mixed with water it will break down very slowly into sugar, taking several years, however, in your saliva there is an enzyme called amylase which can break down starch to sugar in minutes or seconds. A rise in temperature increases the rate of most chemical reactions and a fall in temperature will slow them down. In many cases a rise in 10� C will double the rate of reaction in a cell. This is particle theory. I am going to investigate the temperature at which reactions occur. An increase in temperature will result in a n increase in kinetic energy. Since the kinetic energy increases , the velocity of particles will also increase. Since the speed of particles increases, they should collide more often and therefore the speed of reaction increases. The particles will also have more energy thereby speeding up the reaction even more. ...read more.

Middle

to 40� C using a measuring cylinder measure 10ml of starch from the same solution each time Pour 10ml of starch into one test tube Pour 5ml of amylase into another test tube Put the test tubes into the water bath Put a thermometer into the starch solution Put 2 drops of iodine into each part of the spotting tile When the temperature becomes constant mix the amylase with the starch and start the stop clock at the same time stir twice with a stirring rod for equal agitation stir the mixture twice with the glass stirring rod Every 30seconds remove a small portion of the solution and put into a spotting tile dimple with iodine in Record the time that the solution doesn't change the colour of the iodine Repeat this at a range of different temperatures use ice to reach a lower temperatures change the temperature of the water bath Repeat each temperature twice to get more accurate results Results temperature 14� C Time in minutes colour 1st experiment colour 2nd experiment 0 black black 0.30 black black 1 black black 1.30 black black 2 black black 2.30 black black 3 black black 3.30 black black 4 black black 4.30 black black 5 black black 5.30 black black 6 black black 6.30 black black 7 black black 7.30 black black 8 black black 8.30 black black 9 black black 9.30 black black 10 ...read more.

Conclusion

The proteins structure unravels, which changes the shape of the molecule, and exposes the inner cells of the protein to the killing temperature. The gradient shows that the enzyme is not working as efficiently as it could and therefore needs a greater amount of time to breakdown the starch. This supports my prediction that amylase works best at temperatures slightly below 40� C. My graph showing the rate of reaction between the starch and the amylase shows that as the temperature increases to 40� C the rate of reaction also increases and that as the temperature increases above 40� C the rate of reaction will decrease rapidly. The peak in the rate of reaction is 37� C which is the best temperature for efficient use of amylase. The reason for the decrease in rate of reaction after 37� C is the enzyme is damaged. Evaluation My results proved my prediction to be correct. The breakdown of starch is quicker as the temperature increases until the optimum temperature after which it begins to slow down. I think my results were sufficient to support a firm conclusion, but if I had the chance to investigate further the effect of temperature on the breakdown of starch I would take more results focusing on the higher temperatures and try to pinpoint the optimum temperature. ...read more.

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