The Effect of Temperature on Enzyme Activity

The Effect of Temperature on Enzyme Activity
Investigation -????? The purpose of this investigation is to investigate how temperature affects the speed at which the amylase enzyme breaks down starch by measuring the disappearance of starch using iodine. Introduction -????- Enzymes are protein based catalysts. These catalysts help speed up chemical reactions that take place within a living organism. In this case, the enzyme amylase brakes down the large molecule starch into smaller molecules called maltose. The enzyme will continue to brake down other substrates as long as the enzyme is not denatured. All enzymes are specialised to brake down only a certain type of molecule. For example: The enzyme Lipase will only brake down Lipid molecules (fat), Carbohydrases will only brake down carbohydrate molecules and so on. Being protein molecules they are easily damaged by extreme temperatures. The best temperature for an enzyme to work efficiently is at body temperature of 37ºc, as the temperature raises above 40ºc the enzyme activity decreases as the enzyme is deformed. Also, if temperatures decrease to freezing (0ºc) or below the enzyme activity stops but the enzyme is not denatured
Variables -??? The only factor of the experiment I will change is the different temperatures I will use to compare the rate of enzyme activity. The temperature will range from 10?c to 100?c and the temperature will increase in tens each time. Each sample will be taken in intervals of 30 seconds until no starch is present. Also, the amount of starch and amylase is to be kept the same otherwise the time taken to brake down all of the starch may increase or decrease, resulting in inaccurate results. Any unwanted variation may cause the results to become inaccurate; therefore I will repeat the investigation three times and take an average so the abnormal results will not greatly affect the final results. Hypothesis -???- I predict that the enzyme activity will be at its highest where the temperature is closest to body temperature. As enzymes denature if the temperature is too high I believe that around 60Ëšc the enzyme activity will have decreased sufficiently and will denature completely beyond that. This means that my results should produce an almost-perfect bell curve, where the highest point is at 37Ëšc. Whilst this occurs I should see the iodine black when starch is present, becoming brown/black as the starch is broken down to finally seeing the iodine brown/orange where there is no starch present. Where the temperature is extreme I predict to see no or vary slow and little change in colour to the iodine solution. -?????????????????????????????????- I created the following graph to represent the trend of results I am expecting. [image] Results The following table shows the times for the amylase to completely brake down starch to maltose. Temperature (Ëšc) 1st repeat (mins) 2nd repeat (mins) 3rd repeat (mins) Average (mins) Rate (MÖ¾1) 0 N/A N/A N/A N/A 0 22 (20) 16:30 17:00 16:30 16:30 0.062 43 (40) 06:30 06:30 06:30 06:30 0.159 62 (60) 05:30 08:30 09:00 08:10 0.123 84 (80) 07:30 08:30 09:30 09:30 0.111 100 N/A N/A N/A N/A 0 To enable me to work out the rate of the enzyme, amylase, I used the simple formula: Rate=1/Time The following page shows my actual results for my investigation as a graph. [image] Conclusion The majority of my results produced the expected bell curve on my graph. However, I believe due to human error the results were incorrect between temperatures of 60Ëšc and 80Ëšc causing this area of my graph not to follow the pattern of my initial prediction. I have also noticed that the highest rate is at a slightly higher temperature than I expected, though this may be due to the large difference in temperature between each sample. As the temperature was increases the molecules were given more energy and move around in the solution quicker increasing the chances of collision, speeding up the brake down of starch. I had found that where the temperature was above 40Ëšc the enzyme did not work as efficiently, even with the extra energy, as they had become deformed. Where the enzyme does not work so well or does not even work at all the active site if the enzyme had changed. The enzyme had not died as it is not a living organism. With the shape of the active site changed the enzyme is unable to perform the "lock and key" action the enzyme is meant to do in order to catalyse a reaction. The specified enzyme is shaped to ?lock? on to the substrate. Where the enzyme contacts the substrate is called the active site. When the enzyme becomes denatured the shape of the active site has changed and the enzyme is no longer as efficient. The enzyme can become so deformed that the protein molecule begins to unravel making the enzyme completely useless. [image] Evaluation From the research that I had done and the graph I had produced for my hypothesis, I can see that my results are fairly reliable until 60Ëšc. I do not believe that my test was fair as the temperature which I took samples from did not increase exactly in intervals of 20Ëšc as I had intended. Therefore if I was to repeat my investigation I would attempt to have the temperature exact to my method. I also notice while doing this experiment that some sample were taken every 30 seconds whiles others were taken every 40 seconds. To eliminate this problem the stop clock should be watched carefully and the person taking the sample must be ready well before it needs to be taken. I would also, like the temperature, change the intervals of witch they were taken to increase the accuracy of my experiment. Sometimes it was often hard to differentiate between the changes in colour which could have given inaccurate times. Some one else to do this investigation may have their times different due to their opinion in colour change.

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