Any of the organic compounds making up the genetic material of living cells.
Nucleic acids direct the course of protein synthesis, thereby regulating all cell activities. Their transmission from one generation to the next is the basis of heredity . The two main types, DNA and RNA , are composed of similar materials but differ in structure and function. Both are long chains of repeating nucleotide s. The sequence of purine s and pyrimidine s (bases)
adenine (A), guanine (G), cytosine (C), and either thymine (T; in DNA) or uracil (U; in RNA)
in the nucleotides, in groups of three (triplets, or codons), constitutes the genetic code .