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ENZYME CATALASE Introduction: Enzymes are proteins one of the four macromolecules: carbohydrates, proteins, lipids, and nucleic acids. They are produced by cells to act as a catalyst in chemical reactions. Enzymes are made by the ribosomes within a cell. The enzymes that need to stay within the cell are made by the free ribosomes in the cytoplasm. The enzymes that are made to be exported to other cells are created by the ribosomes on the Rough E.R. The purpose of enzymes is to lower the activation energy (the energy that is put in at the beginning of the reaction) of a reaction; therefore speeding the reaction rate up. Catalase is one of the enzymes found in the cells of the human body. It is made up of five hundred amino acids in four polypeptide chains. It is found in the perioxisome microbody in the cells of eukaryotic organisms. The perioxisomes make hydrogen peroxide (H 2 O 2 ). It is a byproduct of cellular respiration. This is very toxic to cells. That is why catalase is there. Catalase breaks down the hydrogen peroxide before it damages the cell. The formula for the reaction of decomposition of hydrogen peroxide by catalase is: H 2 O 2 H 2 O 2 H 2 O + O 2 H 2 O + O 2 Substrates are the substances that attach to the enzyme. They attach at the enzyme’s active site with induced fit. The combining of and enzyme and substrate requires ATP. The reaction when an enzyme and a substrate join is reversible. The reaction can make more products or it can make more substrate.
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Enzymes are affected by many things; such as salt concentration, pH, temperature, substrate concentration, product concentration, activators, and inhibitors. These things can cause the enzyme to denature (change shape). If the enzyme denatures, then the substrate isn’t able to attach to the active site of the enzyme. The typical salt concentration for an enzyme is intermediate. This allows the substrate to attach to the enzyme correctly. If the concentration is lowered the R groups of the enzyme attract to each other and pull the enzyme into a different shape (changing the active site). If the concentration of salt is raised, then the active site of the enzyme is blocked. Therefore the substrate can’t attach to the enzyme. Enzymes function best in an environment with a pH of seven. When the pH of the enzyme’s environment become more acidic (H + ions increase) the enzyme denatures. This causes the active site to change its shape and the substrate can’t attach. The same thing happens when the enzyme’s environment gains H + ions (becomes more basic). When heat is added to anything the molecules increase is movement.
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