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Investigating how quickly the enzyme catalase breaksdown hydrogen peroxide.

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Biology Coursework - Planning Investigating how quickly the enzyme catalase breaks down hydrogen peroxide I will be investigating the enzyme catalase and the factors affecting the rate at which it speeds up the breakdown of hydrogen peroxide. I will be carrying out this experiment to find out if certain factors speed up the reaction at different rates. An enzyme is a substance that acts as a catalyst in living organisms, regulating the rate at which chemical reactions take place without the enzyme being altered in the process. The name enzyme was suggested in 1867 by the German physiologist, Wilhelm Kuhne (1837 - 1900), and it comes from the Greek phrase en zyme, which means "in leaven". The biological processes that occur within all living organisms are chemical reactions and most are regulated by enzymes. Without enzymes, many of these reactions would not take place at a distinguishable rate. The faster a reaction happens, the more gas it gives off and its temperature increases. Enzymes also have valuable industrial and medical uses. The fermenting of wine, leavening of bread, curdling of cheese and brewing of beer have been practiced from earliest times, but not until the 19th Century were these reactions understood to be the result of catalytic activity of enzymes. The uses of enzymes in medicine include killing disease-causing microorganisms, promoting wound healing, and diagnosing certain diseases. ...read more.


In order to understand the experiment that I am carrying out, it is necessary that I take certain factors and variables into account. There are four possible factors affecting the reaction of hydrogen peroxide that need to be noted. For a given amount of enzyme, the rate of an enzyme-controlled reaction increases with an increase in substrate concentration. At low substrate concentrations, the active sites of the enzyme molecules are not all used - there are simply not enough substrate molecules to occupy them all. As the substrate concentration is increased, more and more sites are used. A point, however, is reached when all the active sites are occupied and the amount of enzyme is the limiting factor, as the increasing of substrate concentration cannot increase the rate of reaction. If the temperature increases, it can affect the rate of an enzyme-controlled reaction in two ways: 1) As the temperature increases, the kinetic energy of the substrate and enzyme molecules increases and so they move faster. The faster these molecules move, the more often they collide with one another and therefore the rate of reaction is faster. 2) As the temperature increases, the more the atoms, which make up the enzyme molecules, vibrate. This breaks the hydrogen bonds and other forces, which hold the molecules in their precise shape. ...read more.


26cm3 21cm3 300 27cm3 23cm3 Gas given off 7cm3 18cm3 From my preliminary I have discovered a few corrections that need to be made in order to perfect my plan. I will also take readings from concentrations of 5% and 15% to give me a larger range from which to draw my conclusions and I will also repeat the experiment twice or three times in order to make sure my results are reliable. I will take an average from which to plot points on my graph. I didn't repeat the experiment twice for each concentration, as I did not have enough time. In my final experiment I will make sure that I have enough time to perform the experiment slowly and carefully. I will also practice starting the stop clock at the precise moment that I put the bung in place so as to get accurate results. I can now reinforce my prediction with the results that I got from my preliminary. I predict that the 5% concentration will react slower than the 10% concentration, as there will be less substrate to make use of the active sites of the enzyme. So too, the 15% concentration will react faster than the 10% concentration but slower than the 20% concentration as it has more substrate than the 10% concentration, but less substrate than the 20% concentration to fill the active sites of the enzyme. ...read more.

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