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Investigation To Show The Affect of pH on Potato Catalase When Breaking Down Hydrogen Peroxide.

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J Neenan, Page 1 of 9 Investigation To Show The Affect of pH on Potato Catalase When Breaking Down Hydrogen Peroxide. Aim. I intend to investigate and carry out a fair experiment that will show how pH effects the potato enzyme Catalase when it is breaking down Hydrogen Peroxide. Background Information. Enzymes are biological catalysts that speed up reactions within living organisms by up to 1020. They consist of large protein molecules and regulate the reaction without being changed themselves. They are very selective of the following: * Most enzymes will only be effective on certain compounds or compound groups. * As the temperature increases so does the efficiency of the enzyme, until about 50 degrees Centigrade, when it becomes denatured. * All enzymes have an optimum pH this is usually the same pH as the environment in which it works. Catalase is the most powerful enzyme known, and in animals is mainly found in the liver, kidneys and red blood cells. It's purpose is to decompose hydrogen peroxide which is a poisonous product of various metabolic reactions. Catalase speeds up the reaction by turning the hydrogen peroxide into harmless water and oxygen as shown in the equations below: Hydrogen Peroxide (aq) ...read more.


I think this plan is the best way possible to carry out this experiment in my cicumstances as I rejected many other methods in a preliminary investigation before this practical. I tried a method where the gas was collected with a syringe, but it was stiff and therefore impractical. There was another method of recording the distance some liquid moved up a "U" tube, but this was inacurate. J Neenan, Page 4 of 9 Safety. As hydrogen peroxide is an irritant and a bleaching agent, lab coats and goggles shall be worn throughout the experiment. This will be in addition to absolute care when handling and standing close to hydrogen peroxide Hypothesis. I predict that the experiment will start off very slowly because the solution is too acidic for the enzyme to work well but will gradually start to increase in pase as each experiment is performed. By pH 6-7 the experiment shall be reacting at full pace. (as this is the natural pH of the potato and enzymes work best at their natural pH.) After this level the experiment will start to slow down again because the solution will be too alkaline for the enzymes to work well. ...read more.


My method could be improved upon by regulating the amount of potato used and making the catalase content equal throughout the sample. This could be achieved by liquidising and weighing the potato sample. Another improvement could be made by extending the range of pH buffers available thus resulting in a more demonstrative range of results. It would be both useful and interesting to know at which levels of pH the catalase is completely inactive. There are two anomylous results in my graph. This is with the pH's 7 and 9. The most likely explanation for these J Neenan, Page 9 of 9 errors is that somehow the pH buffer had soaked in further on these experiments than on the others. This would result in an accelerated rate of reaction and therefore would look out of place on the graph. Another problem with my result for pH 9 is that it has a very large margin of error. This is because my results for this experiment were very varied and inacurate. This can be explained by all the above imperfections in the experiment. I could follow up this experiment by researching the effect of various temperatures on the action of catalase at its optimum pH. This would demonstrate the optimum conditions under which catalase works. ...read more.

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