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Investigate how effectively the enzyme amylase breaks down starch into glucose (to be used for respiration), at different temperatures, and therefore to find the optimum temperature of amylase.

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Introduction

Rough plan, reason and prediction Planning The aim of this experiment is to investigate how effectively the enzyme amylase breaks down starch into glucose (to be used for respiration), at different temperatures, and therefore to find the optimum temperature of amylase. This experiment is a perfect example of digestion at least for the first stage. The first stage is both chemical and mechanical digestion. The amylase breaking down the starch is chemical but your teeth chewing the food is mechanical. The background theory relevant to this investigation involves enzymes in general, amylase itself and kinetic theory. Amylase is an enzyme found in various places in the body, mostly in the saliva and the pancreas. It acts on starch, a polysaccharide, breaking it down into maltose, a disaccharide, or glucose. The above diagram shows how the enzyme and substrate fit together exactly like a lock and key. Each enzyme and substrate are made for each other and are specific. Enzymes are a type of protein, which catalyze chemical reactions. Unlike non -biological catalysts such as charcoal or platinum, which often need harsh extremes of temperature and pH, enzymes must work in the mild conditions of a cell in the body, at approximately 40oC and at a pH between 6.5 and 7.5. I predict that the amylase would break down the starch most effectively at 40oC, and with decreasing efficiency towards 0oC, at which time the amylase would be unable to break down the starch at all. ...read more.

Middle

Time taken for starch to disappear 1 test 2 test Average 20 9 15 12 30 7 10 8.5 40 5 6 5.5 50 6 10 8 60 6* 12 12 70 6* Denatures Denatures * these anomalous results omitted from averages Analysing Evidence Starch was plotted on the y-axis, with temperature on the x-axis: The graph shows that, at MY STARTING TEMPERATURE of 20?C the graph line rose quite steadily until at the temperature of 30?C when the steepness of the line rose much more considerably. But with temperatures over40?the speed at which the starch was turned to glucose began to slow down until after 60?C at which the enzymes in the amylase denatured and failed to work completely, therefore stopping the reaction between the starch and amylase. Therefore I believe that temperatures of 20oC and 40oC, the efficiency of the enzyme increases with temperature. However, the graph between these points is a curve so the efficiency of the enzyme is not equal to the temperature. Between 40oC and 60oC, the efficiency of the enzyme decreases with temperature, mirroring the first part of the graph. The graph shows that the optimum temperature of the amylase tested was 40oC. The graph supports my prediction that the optimum temperature of the enzyme would be around 40oC, and would have decreasing efficiency towards 0oC, at which the amylase would be unable to break down the starch at all. ...read more.

Conclusion

It is likely that there was some solution left over from the previous repetition of the experiment, making the starch/amylase ratio different each time. This could have been overcome by washing out the test tubes between readings. The volumes of each solution could have been made more accurate by measuring the solutions using a narrower gauge measuring tube or by using a syringe. An ideal solution would have been to automate the whole system, with a sample of the mixture being automatically taken every minute, or preferably more frequently, and the concentration of starch stored on computer. This would have overcome the inaccuracies of the timing, which could not always be exact using a stop clock and someone watching it, and would have eliminated the effect of human error from the experiment. If these steps had been taken, it is likely that a graph more similar in shape to that suggested in the prediction would have resulted. I know that I have been critical about quite a few of the things I have done, not done and the equipment I have used now it is time for me to point out some improvements I would make if I re-did my experiment here are some of them: In conclusion, the accuracy of the results was certainly good enough to make a sensible conclusion. If the experiment had been conducted under more strict conditions and with more advanced instruments, the conclusion would not have been different although the individual results might have been more accurate and the graph might have looked very slightly different. ...read more.

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