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The affect of substrate concentration on the rate of a reaction catalysed by the enzyme potato catalase.

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The affect of substrate concentration on the rate of a reaction catalysed by the enzyme potato catalase Introduction Enzymes are protein molecules, which can be defined as biological catalysts. They speed up chemical reactions, but they don't alter throughout the reaction. Enzymes are globular proteins, the enzyme molecules is coiled into a precise three-dimensional shape, with hydrophilic R groups on the outside of the molecule ensuring that they are soluble. They possess and active site, which is a precise shape indented into the enzyme, this acts like a 'lock' for the 'key' that is attached to the substrate of the enzyme. The shape of this active site allows the substrate to fit perfectly, and to be held in place by temporary bonds, then for it to be split into other molecules, or 2 or more molecules to be joined together. When the reaction is finished the products leave the active site and the enzyme is left unchanged and ready to receive another substrate molecule. As enzymes are catalysts they increase the rate at which chemical reactions occur. Most reactions without the presence of enzymes would occur so slowly that they would not happen at all. In many reactions the substrate will not be converted to a product unless it is temporarily given some extra energy, this is called activation energy. ...read more.


5 CP 10 0.5 1.4 2.1 2.7 15 1.2 2.2 3.4 4.7 20 From my selected results I also split them into the 4 different concentrations of hydrogen peroxide tested for ease of use which went as follows: 5cm2 10cm2 1 Minute 2 Minutes 3 Minutes 4 Minutes 1 Minutes 2 Minutes 3 Minutes 4 Minutes 0.1 0.8 1.5 2 0.6 1.5 2.5 3.1 1.3 2.2 3.2 4 2.2 3 3.7 4.4 0.4 0.8 1.2 1.4 1.5 2.4 2.8 3.4 0.6 1.4 1.8 2 1.2 2.4 3.4 4.6 0.8 1.4 2 2.6 1.2 1.8 2.6 3.6 1.9 2.5 3.2 3.8 1.3 2.4 3.2 4.2 0.7 1.2 2 2.8 1 2 2.6 3.4 0.8 1.3 1.9 2.6 1 2 2.8 3.7 0.6 1.2 1.8 2.2 0.8 1.2 1.8 2.2 0.5 1.2 2 2.4 1 2 3 3.8 1.4 2.5 3.2 3.9 1.9 2.8 3.4 4.6 0.6 1.2 1.7 2.2 0.8 1.6 2.2 2.8 0.6 1.2 1.8 2.4 0.8 1.5 2.2 3 0.7 1.4 1.9 2.4 0.9 1.6 2.1 2.7 1 1.4 1.5 1.5 1.6 1.8 1.8 1.9 15cm2 20cm2 1 Minutes 2 Minutes 3 Minutes 4 Minutes 1 Minutes 2 Minutes 3 Minutes 4 Minutes 1.3 2.2 3 4 1.9 3.2 4.5 5.6 3.2 3.8 4.4 5 4.4 5 5.4 5.6 1.7 2.8 3.8 4.6 2.5 3.4 4.4 5.2 1.6 2.8 4 5 2 3.1 4.4 5.4 1.6 2.8 3.8 4.8 1.8 ...read more.


down as there was still a lot of substrate left over and the reaction could still be performed at maximum rate, if this was the case it would not start to slow down until there was significantly less substrate available, obviously this has not been the case. These results do match my hypothesis in that I said as concentration increased, so would the amount of oxygen produced and the rate of reaction would generally be greater. Here is a graph to show the initial rate of reaction for different concentration's of hydrogen peroxide As you can see, as the concentration increases, so does the initial rate of reaction, this is because a greater amount of hydrogen peroxide is available, which means more substrate molecules come in contact with the enzymes (and thus their active site) and can be 'separated' into their products, this is explained simply by collision theory in the introduction. The reason that later on in the reaction the rate of the reaction may be different is because there is likely to be less substrate left over as the reactions occurring would have separated them into their products, hence the reaction rate would not be going as fast. Appendix Mean Added up all the entries, then divided them by the number of entries there were. E.g. The mean for 1.1 1.3 1.2 1.4 Would be (1.1+1.3+1.2+1.4)/4 which equals 1. ...read more.

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