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Biology -The Effect of Temperature on Enzymes

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Biology coursework - Polly Skeats-Beswick 3 February 2002 THE EFFECT OF TEMPERATURE ON ENZYMES Enzymes are catalysts that speed up chemical reactions. They work on substances called substrates. The reaction takes place on a part of the surface of the enzyme called the active site. This how the enzyme works: Aim: To find out what effect different temperatures have on enzymes. To do this, I have planned an experiment with trypsin (which contains enzymes) to see how it breaks down substrates (such as the ones found on photographic film), at a variety of different temperatures. Plan: I am going to: * Design and set up an experiment that will effectively monitor the results * Measure and evaluate the results, using graphs * To help me predict what will happen, I am going to read books and gather research into the subject of enzymes e.g. in the digestive system and washing powder Safety Enzymes are irritants, therefore I will have to wear safety goggles and because I will be in the science lab, I will tie back my hair and tuck in any loose clothing. I took great care with the experiment because I was dealing with hot liquids. ...read more.


Using a fresh photographic strip, I repeated this part of the experiment twice more, to give me three readings against each temperature, from which I could then take an accurate and meaningful average. I then turned up the temperature of the water bath at 5�C intervals, recording the results again three times each. I ended my experiment when the temperature reached 70�C. Fair Test: I ensured this was a fair test by doing the following: * Doing all the tests on the same day because sometimes there are conditions out of our control that can change * Checking with universal indicator paper that the pH value of the trypsin was always the same, because enzymes denature when exposed to pH values greater or less than seven. * Checking that the concentration in the test tube was always the same: 0.5% trypsin, to ensure balanced results * Making sure the temperature on the thermometer was exactly as it should be when recording my stopwatch results * Using the same type of photographic film and the same height and length Predictions I think that as the temperature increases, so will the enzyme's rate of reaction, but I think when it gets to a certain temperature, the enzymes will begin to denature and will not react as quickly. ...read more.


The graph also shows that the enzymes then start to denature at around 65�C because the line shoots up. Here, the film takes radically longer to become transparent, eventually causing the trypsin to have no effect on the photographic strip. A line of best fit would only be appropriate between 45 and 65�C. These results fitted in with my predictions because the enzymes did increase their rate of reaction when the temperature increased and did denature at a high temperature. Evaluation I thought my experiment worked well because it showed similar readings and I didn't have any odd-looking figures within the results. I also thought the results were accurate enough, because it gave such a clear pattern of the enzymes' behaviour. If I wanted get obtain even more accurate results, I could have tested at an even greater number of temperatures. I think my method was the best way of carrying out the investigation because I took more than two results to reach my conclusion. I could improve my method by taking even more results. To provide me with even more evidence for this investigation, I could compare notes with other students who have carried out the same experiment, to see if there are any anomalies. * * * ...read more.

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