DNA. Computer illustration of part of a molecule of beta DNA (deoxyribonucleic acid), the genetic material found in all living cells, in front of a genetic sequence. Beta DNA spirals clockwise when viewed from above. The spherical atoms are colour- coded: oxygen (red), phosphorus (orange), carbon (white), hydrogen (light blue) and nitrogen (dark blue). DNA encodes and transmits the hereditary characteristics of living organisms. It consists of two strands, each having a sugar-phosphate backbone linked by paired nucleotide bases to form a double helix. The sequence of these four bases, cytosine (C), guanine (G), thymine (T) and adenine (A), determines each person's unique genetic code.