Investigate the Effect of pH on Immobilised Yeast Cells on the Breakdown of Hydrogen Peroxide

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Investigate the Effect of pH on Immobilised Yeast Cells on the Breakdown of Hydrogen Peroxide Safety: ======= * Extreme alkaline and acids are used so must wear gloves, goggles and apron. * Be very careful not to make contact with any of the chemicals, as they will be irritable and some corrosive to the skin and eyes. * There must be no running and any other normal laboratory rules should be followed as usual. * Hydrogen peroxide is corrosive and so should not be touched. * A lab technician should immediately wash up spillages. * Always be careful of the glass instruments as these could break. Background knowledge: In my experiment I will be measuring the amount of oxygen given of in a gas syringe over a certain time period from different pH levels. Hydrogen Peroxide is a chemical compound, H2O2, a colourless, syrupy liquid that is a strong oxidizing agent and an in water solution a weak acid. It is miscible with cold water and is soluble in alcohol and ether. Although pure hydrogen peroxide is fairly stable, it decomposes into water and oxygen when heated above about 80°C; it also decomposes in the presence of numerous catalysts e.g. most metals, acids. The properties and factors that effect breakdown of Hydrogen Peroxide are important in this investigation. The reaction of Hydrogen Peroxide forms water and oxygen, which is shown in the equation below. 2H2O2 2H2O + O2 On it’s own this reaction is very slow and normally a catalyst is needed to speed up the reaction. A catalyst is used to speed up reactions without it getting used up. So a biological catalyst such as an enzyme is used to speed up the process in the equation above. In my experiment I am going to do I am using dried yeast, which contains a suitable enzyme ‘catalase’. So therefore I am using the catalase in the yeast to speed up the reaction, the products being produced and the overall results. To explain why enzymes speed up reactions it is based on the collision theory. The enzyme’s, which are immobilised in the yeast-based beads, will give many active sites for the substrate (Hydrogen Peroxide) to bind (‘lock’) with. This will increase the collisions and therefore the rate of reaction. Immobilised enzymes can be washed and re-used. The beads are all relatively the same size so that there is less chance of error on the investigation. Immobilised enzymes are also more stable in extremes of temperature and pH, which it will need for my experiment. A buffer solution is one, which resists changes in pH when small

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