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Effect of Temperature on Enzyme Activity

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AP Biology lab # 4 Thomas Selby Mrs. Lipinski 10/10/03 Effect of Temperature on Enzyme Activity Abstract The objective of this experiment was to determine the effect of temperature on the rate that enzymes work. The purpose was to determine whether increasing the temp made the enzymes more active, and if so, at what temperature does the activity start to decline. The experiment consisted of thirty test tubes, with 5 test tubes at each temperature. The temperatures used were 10, 20, 30, 40, 50, and 60 degrees Celsius. For each temperature there were four test tubes with a sucrose substrate, a buffer, and an enzyme, and one test tube with just sucrose substrate, a buffer, and distilled water. After the liquids were mixed and left for exactly twenty minutes, DNS was added to each test tube and then each tube was boiled for 10 minutes, and finally the test tubes were removed from any heat and distilled water was added. Finally the blank test was placed in the photo spectrometer, and the results were compared the other four test tubes to determine the absorption rate for each temp. Compared with the best fit line for the given data, the average absorption was plotted and then calculated to determine the micro-moles of sucrose at each temp, and from there the rate of micro-moles of sucrose per minute. ...read more.


The test tubes were placed in boiling water when the DNS was added to speed up the particles and to make sure everything that could react, did. Methods and Materials Initially, fairly large beakers containing tap water were heated to temperatures between 10 and 60 degrees Celsius at 10 degree intervals. When the water in these beakers reached the desired temperature, using whatever method necessary, the water was manipulated to stay at the temperature for as long as necessary, at least 30 minutes. After the desired temp was reached, 5 test tubes for each temperature were prepared, and each test set of test tubes was numbered 1-4, and B. All 5 test tubes were initially filled with .5ML of the sucrose substrate, and .5ML of the buffer. After that four of the test tubes had .5ML Invertase added, while the other had .5ML of distilled water added. Once all the necessary solutions had been added, the set of 5 test tubes, (one control and four with enzyme) for each temperature level were added to the temperature specific bath. The test tubes were placed in the bath in such a way that the test tubes would rest inside the beaker, with the heated or cooled water effecting the temperature inside the beaker. However there would be no contact between the heated water and the solutions inside the test tube. ...read more.


As the bonds break the enzyme no longer holds its active site to a specific shape, and when the active site lacks a specific shape it is no longer able to hold out H20, it is no longer to promote acid base reactions, and most importantly it is not able to hold on to a substrate. The results obtained in this experiment match previously recorded data from similar experiments, and matches conclusions drawn in many sources, including the AP Biology text book. The data supports the conclusion that as temperature increases, so does enzyme activity, until a certain point, where the enzyme begins to denature and will eventually not function at all. All the information listed above in different sections, including the graph and the basic information provided in the introduction supports these conclusions. Conclusion In conclusion, it is clear that temperature has an important effect on enzyme activity. It is also clear that enzymes are more productive at some temperatures than at others. Starting at 10 degrees Celsius Invertase was not that active. The amount of Invertase activity increased until it peaked at 50 degrees Celsius, and then declined at 60 degrees Celsius. From the data it is clear that the optimum temperature for Invertase activity is between 40 degrees Celsius and 50 degrees Celsius. To sum it all up, the activity of Invertase depends a lot on temperature, and with a temp that is too low or too high, there would be little or no sucrose breakdown. ...read more.

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