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The Affect of Changing Temperature on Amylase Activity

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The Affect of Changing Temperature on Amylase Activity Introduction Enzymes are biological catalysts that are constructed from polymers of amino acids. The amino acids are constructed in a very long chain. These polypeptide chains coil over to form a very precise three-dimensional structure - this is known as a globular structure. On the surface of enzymes there is an area called the active site. Enzymes are specific this means that only certain substances have a complementary shape to fit the enzymes active site, this is called a substrate. Once a substrate attaches itself onto the enzymes active site, a substrate complex is formed; this then splits to make products. Enzymes increase the rate of reactions, by lowering the activation energy. This is the energy required to make molecules react together once a collision has taken place. There are four factors, which affect an enzymes ability to function properly; these are substrate concentration, enzyme concentration, temperature and pH. With a low substrate concentration many active sites on the enzymes are unoccupied so rate is slow. Increasing substrate concentration will mean an increase of them in the solution; the result is that there will be a higher chance of a collision between the enzymes and the substrates, therefore rate of reaction speeds up. With a low enzyme concentration there is competition for the active site wanted by the substrates consequently rate is slow. ...read more.


This enabled us to test each temperature a minimum of 5 times to give an average for a more accurate result. Rate (s-�) Temperature 1 2 3 Average 0�C - 3.7 2.4 2.03 30�C 3.5 5.8 5.6 5.0 40�C 6.5 6.4 6.3 6.4 50�C 5.0 5.8 5.4 5.4 60�C 5.4 7.0 4.3 5.6 70�C - - - - Conclusion At the beginning of the investigation I predicted that amylase activity would increase up until 40�C because most chemical reactions increase in rate. After this temperature I believed that the rate would decrease because the amylase will become damaged. From 60�C onwards I think that the rate will have almost stopped and at 70�C the enzyme will have become denatured. My results support most of my hypothesis; I see that I was correct in saying that amylase activity would increase. This is because as molecules heat up they gain more kinetic energy this makes them move around faster, which increases the chances of a collision. The fastest rate was at 40�C - which was what I predicted. The rate was fastest at this temperature because the temperature provided enough kinetic energy to supply the molecules with to make successful collisions, but not so high that the temperature broke the hydrogen and ionic bonds of the amylase - if this were to happen then the enzyme would have denatured. ...read more.


This is because 37�C is much closer to 50�C. The graph would look better if 50�C and 60�C swapped positions. I think the following things could have affected my results: Students may not note a colour change correctly. Too much amylase could have been added therefore making the rate too fast, which could have happened at 60�C. It would be too fast because there would be more enzymes to react with the starch molecules. Not enough amylase may have been added therefore the rate would be too slow, for example 50�C. Not enough enzymes would be present to react with the starch. Excessive amounts of starch could have been used making the rate too slow because there are not enough enzymes for the starch. Too little starch would make the rate happen too quickly because there is less starch for the enzymes to work with. Results could have been affected by incorrect temperature of the water-baths. People could have misread the stop-clock. We may not have left the test tubes in the water-baths for a long enough to reach the desired temperature. Limitations We could have used a spectrophotometer to measure absorbency rather than relying on our own vision to note colour change. Our water-baths could have been set up incorrectly or they could be faulty. The temperatures, which we experimented with, were not chosen by us. Time was a restriction because it was not possible for every single group do perform every temperature. More repetitions would result in a better mean value. Carol Goodman ...read more.

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