Biological Reactions Of Chemical Reactions Essay

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There are thousands of chemical reactions that occur in an organism that make life possible. Most of these chemical reactions occur too slowly on their own. Enzymes are protein catalysts that speed up chemical reactions in a cell. Catalysts are not changed by the reactions they control, and are not used up during the reaction. Enzymes therefore, can be used over and over again. Enzymes are large complex proteins made by the cell and allow chemical reactions to take place at the temperature of the cell. These catalysts are needed in only very small amounts because a single enzyme molecule can complete the same reaction thousands of times in one minute.
Each enzyme is very specific and can only catalyze a certain reaction. The specific reaction catalyzed by an enzyme depends on the molecular structure and shape of a small area of the enzyme’s surface called the active site. The active site an attract and hold only its specific molecules. The target molecule that the enzyme attracts and acts upon is called the substrate. The substrate and the active site of the molecule must fit together very closely. Sometimes the enzyme changes its shape slightly to bring about the necessary fit.

A chemical reaction requires that bonds in the reactants be broken. The initial energy that must be absorbed in order to break the bonds of the reactant molecule is called the energy of activation. Enzymes work by lowering the energy of activation. For example,
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