Regulation of Cell Functions

In all cells, the information necessary for the regulation of cell function is contained in strands of deoxyribose nucleic acid, or DNA. The nucleic acids are large polymers of smaller molecular subunits called nucleotides, which themselves are composed of three basic molecular groups: a nitrogenous base, which is an organic ring contain ing nitrogen; a 5-carbon (pentose) sugar, either ribose or deoxyribose; an inorganic phosphate group. Nucleotides may differ in the first two of these components, and consequently there are two specific types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

There may be any one of five different nitrogenous bases present in the nucleotides: adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U). These are most often denoted by the letters A, C, G, T, and U, rather than by their full names.