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Biology -The Effect of Temperature on Enzymes

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Introduction

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.

Middle

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.

Conclusion

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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