Honors Biology Milestone Assignment 1
Enzymes are a substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction. They are responsible for thousands of metabolic processes that sustain life. Enzymes are highly selective catalysts, greatly accelerating both the rate and specificity of metabolic chemical reactions, from the digestion of food to the synthesis of DNA. Most enzymes are proteins, although some catalytic RNA molecules have been identified. Enzymes depend on temperature, ionic conditions, and pH of the surroundings. Chemical equilibrium is the state in which both reactants and products are present in concentrations, which have no further tendency to change with time. Usually, this state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but equal. Thus, there are no net changes in the concentrations of the reactant(s) and product(s). Enzymes allow many chemical reactions to occur within the homeostasis constraints of a living system. Enzymes function as organic catalysts. A catalyst is a chemical involved in, but not changed by, a chemical reaction. Many enzymes function by lowering the activation energy of reactions. By bringing the reactants closer together, chemical bonds may be weakened and reactions will proceed faster than without the catalyst. Enzymes can act rapidly, as in the case of carbonic anhydrase, which causes the chemicals to react 107 times faster than without the enzyme present. Carbonic anhydrase speeds up the transfer of carbon dioxide from cells to the blood. There are over 2000 known enzymes, each of which is involved with one specific chemical reaction. Enzymes are substrate specific. The enzyme peptidase (which breaks peptide bonds in proteins) will not work on starch (which is broken down by human-produced amylase in the mouth). Enzymes are proteins. The shape of the protein determines the functioning of the enzyme. The arrangement of molecules on the enzyme produces an area known as the active site within which the specific substrate(s) will "fit". It recognizes, confines and orients the substrate in a particular direction.
In a chemical equilibrium, the concentrations of reactants and products do not change. But the forward and reverse reactions have not stopped - they are still going on at the same rate as each other. Imagine walking the wrong way on an escalator - at the same speed as the escalator, but in the opposite direction. Your legs would still be walking forwards, and the escalator would continue to move backwards. However, the net result would be that you stay in exactly the same place. This is what happens in an equilibrium.
Enzymes depend on many things such as temperature, concentration of substrate and product, activation, and changes in ph. Temperature increases in temperature will speed up the rate of non enzyme mediated reactions, and so temperature increase speeds up enzyme mediated reactions, but only to a point. When heated too much, enzymes (since they are proteins dependent on their shape) become denatured. When the temperature…