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In this investigation, I am aiming to investigate the effect pH has on the activity of the enzyme, Trypsin.

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Introduction

Aime´┐Ż Allam Biology Coursework: Trypsin Investigation Planning Section: In this investigation, I am aiming to investigate the effect pH has on the activity of the enzyme, Trypsin. Factors affecting the activity of Trypsin: -The pH This is the independent variable. I will investigate this factor. -The temperature of the surroundings. -I will control this by doing all the tests at room temperature. This way it won't affect my results. -The concentration of Trypsin. -I will control this by using a solution of Trypsin of 5% concentration for all my tests. -The concentration of Gelatin. -I will control this by using pieces of photographic film that are exactly equal in size: 1cm squared Preliminary Testing: I performed a preliminary test to see which strength of Trypsin (1%, 3%, 5%) would be the most efficient to use, given the time we are allowed to perform the experiment. Apparatus: Test tubes x3 Test tube rack Timer x3 PH 9 buffer solution Trypsin in the following strengths: 1% 3% 5% Spatula x3 Method: -Firstly, 3cm cubed of the buffer solution (ph 9) was put into the three test tubes. -Then a piece of photographic film 1cm by 0.5 cm square was added to each tube. -A timer was positioned in front of each tube. -Then 1cm cubed of the 1% strength Trypsin solution was added to a boiling tube. ...read more.

Middle

The enzyme's active site and the molecule of the substrate fit together like a key in a lock. The more concentrated the enzyme, the faster the reaction. This is to do with kinetic theory as the greater the number of enzyme molecules around the substrate, the more likely that a high-energy collision will occur, meaning that the reaction will be faster. The temperature of the surroundings has an effect on the enzyme's activity. The higher the temperature, the faster the reaction is. This is true up to a certain point. Again kinetic theory is used to explain this: when the enzyme molecules are hot they move around more and a lot faster, this means that a collision with the substrate is much more likely. This is only true up to a certain temperature (very high or very low), when the enzyme becomes denatured. This means that it can no longer work because the active site's shape has changed. Lastly, all enzymes have an optimum point. This is a set of conditions that it works best at. For the enzyme that will be used, Trypsin, this is pH 8 and roughly 37.5 degrees Centigrade. Prediction: I predict that the photographic film will go clear in the quickest time when the test is performed at pH 8, because in my research I found that Trypsin likes to work at this pH. ...read more.

Conclusion

4) I would do at least 5 repeats altogether. This would make the margin for error much narrower. If I do the tests 5 times then take an average it will be much more accurate. Limitations: I split the practical over two days. As I was performing it at room temperature, this is a limitation. I did not take the temperature on either day. This means that it could well have been colder on one day than the other. As temperature is a factor affecting Trypsin's activity, it is not a fair test, as it was not kept constant. In the actual laboratory that I was doing the tests in, the temperature might have varied as there are parts of the room that are colder than the rest e.g. near the window and draughts. The photographic film was not measured and cut with absolute precision so it may have been different sizes. The Accuracy Of My Results: I think that, given the materials I had available to work with, m results were fairly accurate. There were no anomalies in my results. The fact that I did some repeats meant that there was a greater chance of my results being correct. The Extension Of This Investigation: To extend this investigation I could further prove my conclusion by testing the rate of Trypsin in the same pHs but also investigate the ones in between the whole numbers. Eg look at the rate of the following pHs: 9.0, 9.2, 9.4, 9.6, 9.8, and 10.0. This way it would show my theory in greater detail. ...read more.

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