Genetic origins of amino acids Constituents and organisation of DNA DNA (deoxyribonucleic acid) is the genetic coding scheme used by all living organisms to pass on the hereditary programme to the next generation. DNA consists of two cross-linked polynucleotide chains, having an overall length of about 2 metres, which, for eukaryotes, is stored within the nucleus of a cell. The nucleus occupies about 10% of the cell volume and is isolated from the cytoplasm by the nuclear envelope, which consists of inner and outer bi-layer lipid membranes. This double membrane is interspersed with a significant number of pores.
