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Toinvestigate a factor affecting the rate of  breakdown of sucrose by the enzyme sucrase.

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To investigate a factor affecting the rate of breakdown of sucrose by the enzyme sucrase Background information. Sucrose is normally found in most plants, and it is in a form, which most carbohydrates are transported in plants. But most commonly it is found in sugar cane and sugar beet in a concentrated form. Sucrose is actually table sugar that could be bought from and local supermarket for sweetening tea or just for general cooking. This sugar is extracted from the sugar cane and the sugar beet. A sucrose molecule is 2 monosacaride joined together to form a disaccharide, these are glucose and fructose. A sucrose molecule needs to be broken down before it can be used as energy in respiration, and the enzyme that does this is sucrase. An enzyme is a biological catalyst, which speeds up reactions. They are made up of protein and only work on specific substances. Aim The aim is to see what affects the enzyme, sucrase breaking down the substrate sucrose. The sucrase is supposed to break the sucrose back into fructose and glucose. ...read more.


The amount of substrate and enzyme in each of the experiments will be kept the same by using the same concentration and volume. Temperature Enzymes work better in higher temperature; this is due to the kinetic theory that when there is more energy (in this case heat) molecules will speed up. In this experiment the enzyme molecule will speed up and will make more frequent contact with the substrate molecule meaning greater reactivity. However enzymes don't work very well when they get too hot, this is when it begins to denature. When it gets even hotter the enzymes get permanently destroyed. Heat destroys the hydrogen bonds in the enzymes so that the shape and the flexibility are changed. So the active site has been modified. Before the temperature gets to the level that it is dangerous for the enzyme there is an optimum point of reaction. So the rate of reaction works best. The optimum temperature is normally about 40 �C. My prediction about sucrase's optimum point is at 37.5�C because that is the temperature in our body, and surcrase works at optimum levels in our body breaking down sucrose into energy for respiration. ...read more.


Repeat this test with the same amount of substrate and enzyme, with the same temperature two more times to show that the results are correct. This test needs to be done at different temperature, it is suggested to do them at: 5 �C 15 �C 25 �C 35 �C 37�C 40 �C 45 �C 55 �C 65 �C ?Q10? ?Optimum? ?Denature? The optimum temperature that has been predicted by myself has been added to prove at that temperature is where the rate of reaction is highest. These temperatures are to see how quick the rate increase, where is the optimum and when does it denature. The results from the experiment will be plotted down in a table showing the time taken in the 3 test tubes in the first set of readings of 5 �C, then 10�C etc. With an average at the end of each What should happen is that, when the temperature is at 37.5�C, which is the fastest rate of reaction (so sucrose is broken down into glucose very quickly) and any temperature after that will make that reaction very slow. Before the optimum rate, the rate of reaction should be increasing steadily. This is because of the kinetic theory, and it denatures because too much heat change's their active site. ...read more.

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