The Effect of Temperature on the Rate of Respiration in Yeast

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The Effect of Temperature on the Rate of Respiration in Yeast I have chosen to investigate the affect temperature has on the rate of respiration in yeast. I will use an experiment to determine whether the yeast's rate of respiration will be quicker, slower or if it does not change when the temperature is varied. Scientific Knowledge The first thing to say about enzymes is that they are proteins and they are found in all types of organisms from humans to viruses. They function in the body as catalysts. In other words they speed up the rate of chemical reactions in the body. Enzymes actually accelerate chemical reactions by a factor of about 1 million. Enzymes are organic catalysts. Without enzymes the metabolism of an organism would be too slow for the organism to survive. The word enzyme actually means "in yeast" as they were first discovered in these micro-organisms. ---------------------------------------------------------------------- Enzymes are found inside and outside cells. Enzymes found outside cells are for example, those that control metabolism while enzymes found inside cells for example, gut digestive juices and the enzymes secreted by bacteria, which digest their food outside the body then reabsorb the products. Enzymes work on particular organic chemicals, these are called substrates. So food is the substrate of digestive enzymes. -------------------------------------------------------------------- The lock and key hypothesis attempts to explain how enzymes are specific to particular substrates and how they may work. In this hypothesis the enzyme is the lock and the substrate(s) is the key. Enzyme molecules have a particular shape like a lock and only a particular substrate (key) can fit into that lock. The part of the enzyme that binds the substrate is called the "active site". Just like other catalysts, after the enzyme has been involved in the reaction it

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