Enzymes are biological catalysts that support almost all of the chemical reactions that maintain animal homeostasis. They are formed at cell sites known as ribosomes. Amino acids, which are the building blocks of proteins, are brought to the ribosomes and strung together in a precise manner to for enzymes. They then float free in the cell or into nearby body areas where they are needed (Compton's Encyclopedia, 1999).

      Plants in photosynthesis use enzymes, which is the process by which plants obtain food from sunlight. Enzymes also help plants and animals get energy from their food. Energy is released from digested food by oxidation of the individual cells of plants and animals. By this process, oxygen, normally obtained from the air, receives electrons from the breakdown products of sugars, fats, or proteins to release the energy they contain. In living things, oxidation must take place slowly to minimize heat which is destructive. It does this through a series of enzyme-controlled reactions that release heat and energy in small amounts (Compton's Encyclopedia, 1999).

      Most reactions in cells and organisms are catalyzed by enzymes, which are regenerated during the course of a reaction. The biological catalysts are physiologically important due to the fact that they speed up the rates of the reactions that would otherwise be too slow to support life. They increase reaction rates up to as much as one millionfold, but more often by about one thousand fold. Catalysts speed up the forward and also reverse reactions equally so that even though the magnitude of the rate constants of the forward and reverse reactions are increased, the ratio of the rate constants remains the same in the presence or absence of enzymes. Since the equilibrium constants is equal to the ratio of rate constants, it is obvious that enzymes have not effect on the equilibrium constant of the reactions that they catalyze (King, 20).

WORKS CITED

Compton's Interactive Encyclopedia, 1999. The Learning Company

King, Michael W., Ph D, Enzymes, http://web.indstate.edu/thcme/mwking/enzymes.html Page 20