NSES: Life Science: Heredity Molecular Basis - 1 In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA
1 In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A, G, C, and T). The chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular 'letters') and replicated (by a templating mechanism). Each DNA molecule in a cell forms a single chromosome.