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Experiment to investigate the effect of varying surface area hence varying the amounts of Catalase on the breakdown of Hydrogen Peroxide.

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Introduction

Experiment to investigate the effect of varying surface area hence varying the amounts of Catalase on the breakdown of Hydrogen Peroxide Aim: to investigate the effect of the amount of catalase and the breakdown of hydrogen peroxide. Hypothesis: Hydrogen peroxide will breakdown to oxygen and water in the presence of catalase. The enzyme catalase carries out the following reaction: 2H2O2 2 H2O (l) + O2 (g) Catalase is an enzyme, enzymes are globular proteins that have tertiary structures with hydrophilic R groups that form a precise active site which is substrate specific to hydrogen peroxide substrate. Hydrogen peroxide substrate and the catalase enzyme join to form the enzyme substrate complex. Temporary bonds are formed until the active site of the enzyme splits the toxic substrate hydrogen peroxide into two harmless products, oxygen and water. This process happens naturally but slowly, catalase lowers the activation energy so the reaction happens more quickly without the need for more heat which can damage living cells. The reaction with catalase happens in living creatures as hydrogen peroxide is a toxic waste product of certain metabolic reactions such as respiration. Hydrogen peroxide is used by neutrophils to kills bacteria after it has engulfed it as hydrogen peroxide is a powerful oxidiser and therefore punches holes in the cell wall of the bacteria. I found this information on www.h202-vu.com and biology one. I predict that the higher the amount of catalase exposed to the hydrogen peroxide the faster the rate of reaction. ...read more.

Middle

In an enzyme catalyzed reaction, this increases the rate at which the enzyme and substrate molecules meet and therefore the rate at which the products are formed. The results would not provide accurate comparisons if the temperatures change. Therefore I will be using tongs to handle the apparatus so that the heat from my hands will not affect the Catalase and measure the temperature of the hydrogen peroxide before I fill the syringe each time. I will also keep the amount and concentration of hydrogen peroxide the same so the chip is as submerged as possible. The concentration will start at 20 vol. for each surface area, if the hydrogen peroxide was too strong it would break the bonds of the enzyme therefore the tertiary structure of the active site would change causing it to be denatured. This is due to the hydrogen ions in the acid interacting with the r-groups of the enzyme form the tertiary structure, too many hydrogen ions would be effecting the r-groups. One factor I will need to take into consideration is the fact that hydrogen peroxide has an acidic pH which will break down into water which has a neutral pH. This may effect the enzyme action as many enzymes work faster in a neutral environment, the only control over this is the fact that it will happen in each test and to consider its effect at the end of the experiment. ...read more.

Conclusion

Therefore at the point of my anomalous result the chip section may have all been submerged, therefore making a higher reading of gas. This aspect combined with the evidence for the enzyme preferring a neutral environment my have made the anomalous results higher than expected. A factor that could have affected accuracy may have been syringeing in the hydrogen peroxide. I tried to keep the action as similar as possible however there is no firm control of this. This is why I took an average of three readings of gas at each time. The average would minimise the effect that inaccurate reading has. The method proved my prediction as the rate of reaction clearly increased as the surface area was increased. However if I wanted to see the full rate of reaction of the enzyme action I should have recorded the reading until no further gas is produce and until the solution is water. This should a cumulative curve, all surface area readings would eventually finish at the same point. Lengthening the experiment would make good extension work. The results are relatively accurate and support a firm conclusion even when considering the variables that could not be controlled (chips floating occasionally and acidic environment turning neutral). If I repeated the experiment using a buiret and a gas syringe instead of glass measuring cylinder and the results were similar to my previous ones, the reliability of the results would become even stronger. Using a buiret would be more accurate as they are clearer to read. Voirrey Fermor 21/03/03 ...read more.

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