ABSTRACT
The highly ordered, but extremely complex nature of living cells is due to the great variety of organic compounds which may be formed, inherent in the chemical properties of carbon itself. Its ability to form four covalent bonds with other atoms and itself, generating long carbon chains, gives rise to an almost limitless number of possible compounds, including macromolecules with molecular weights as high as 100 million. In all cases, these macromolecules are formed from the linkage, in a series, of smaller molecules, termed monomers, and hence are called polymers. Even if constructed from a pool containing a relatively small number of different types of monomer molecules the number of different possible sequences of these subunits is theoretically very large indeed. If only a small fraction of all of the possible combinations of monomers were to be associated with a distinct structural or functional characteristic of the polymer molecule, this number would be more than sufficient to account for the enormous diversity and complexity of living organisms. There are, however, a large number of characteristics common to all cells, irrespective of their origins, which is indicative of a moderately consistent selection of only a few of the possible combinations in each case, suggesting that cellular chemistry is organized and regulated in a highly precise manner.
