DNA. Computer illustration of part of a molecule of beta DNA (deoxyribonucleic acid). Beta DNA spirals clockwise when viewed from above. Atoms are seen as spheres. DNA encodes the hereditary characteristics of living organisms. It consists of two strands that wind around each other in a double helix. The strands each have a sugar- phosphate backbone (pink) connected by paired nucleotide bases (blue and green). The sequence of the four types of base determines the genetic code in the form of genes.