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The aim of the experiment is to determine the effect of temperature variation on the rate of an enzyme reaction. We choose hydrogen peroxide as substrate, and catalyse as the enzyme.

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Introduction

THE EFFECT OF TEMPERATURE VARIATION ON THE RATE OF AN ENZYME REACTION Aim: The aim of the experiment is to determine the effect of temperature variation on the rate of an enzyme reaction. We choose hydrogen peroxide as substrate, and catalyse as the enzyme. The latter ingredient is contained in potatoes. In fact, equally sized pieces of potato are involved in the experiment. The following equation predicts the outcome of the reaction between the mentioned reagents: Hydrogen peroxide + catalyse = water + oxygen We measure the rate of reaction by observing the amount of oxygen given off. List of equipment: The apparatus employed in experiment consists of the following items: * Beakers * Thermometer: to measure the temperature of the substrate * Stop clock * Delivery tube: the oxygen given off will travel through this tube * Potato: enzyme catalyse is contained in the potato * Hydrogen peroxide: substrate * Bunsen burner: to heat up the hydrogen peroxide at the chosen temperatures * Seringe : to suck up a particular amount of the substrate, so each test tube has the same amount of substrate. * Test tubes Method: The experiment involves an enzyme found in all living cells, catalyse, causing hydrogen peroxide to decompose into water and oxygen. The main response variable we observe is the rate of the reaction, as reflected by the amount of oxygen released. This we measure with the aid of a delivery tube, that is, by counting the number of oxygen bubbles coming out of the tube. The greater the count, the faster the reaction. ...read more.

Middle

This is, indeed, the reason why few cells can tolerate higher temperatures than approximately 45�C. The mechanism of heat-induced structural denaturation of the enzyme is well understood at a molecular level. The heat breaks the hydrogen bonds between distant parts of the polypeptidic chain of the enzyme, so that the protein loses stability of its three-dimensional conformation. Because such stability is so essential to chemical function, any temperature increase resulting in a structural collapse of the protein will reduce or totally block the enzymatic activity. Therefore I predict that heating the Hydrogen peroxide beyond a certain temperature threshold will gradually kill the experiment reaction. Fair test: To make the test fair, the following parameters must remain constant during the course of the experiment: (1) the amount of water in the beaker, (2) the amount of Hydrogen Peroxide and Catalyse, (3) the duration of reaction , and (4) if possible the room temperature. It is very hard to keep the room temperature constant, since the experiment will be run during different days, and it is very likely to have a change of temperature during the intervals of time between one day and another. If the reaction happens too quickly, I will have to dilute the substrate, to balance out the reaction. I will report accurate results, in order to insure that the test is done fairly. Experimental results A result table of the No. of bubbles given off at different temperatures Temperature (�C) ...read more.

Conclusion

For all the other parts of the experiment I have tried to be as fair as possible: the amount of potato put in the tube was cut with the same size instrument all the time, the potato had been conserved in a suitable place for the whole duration of the experiment, so the enzyme inside it would not get denatured. I didn't gain any anomalous results from the experiment, apart from in the first attempt at it, when the range of temperatures didn't give a clear enough idea of the pattern the reaction was taking. To improve my method, I could be more precise on the counting of oxygen given off from the reaction. I could use a measuring cylinder to get the amount of oxygen given off in ml, which would be certainly more accurate then me counting the bubbles given off. I could investigate further how the enzyme's rate of reaction varies with temperatures below 20�C. I already know that at low temperatures enzyme's have a slow rate of reaction, but my curve would be more complete, and my theory would be clearer. I would have as my minimum temperature 0�C and a range of temperatures that would go up to 50�C in fives, keeping the condition of experiment as constant as possible. I can also repeat my experiment many times in order to measure the variability between experiments. Despite this I consider my results clear enough to prove my beginning prediction. ...read more.

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