DNA molecule. Computer artwork of the molecular structure of a DNA (deoxyribonucleic acid) double helix. DNA carries the genetic code, which controls and transmits an organisms hereditary traits. The helix is composed of two twisting sugarphosphate strands, linked on the inside of the helix by complementary pairs of nucleotide bases. There are four types of nucleotide base; adenine, guanine, cytosine and thymine. The sequence of base pairs, arranged in discrete segments known as genes, determines the genetic code.
