Deoxyribonucleic acid (DNA)

Deoxyribonucleic acid (DNA): The molecule that encodes the genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides to form a double helix. The four nucleotides in DNA contain the bases: adenine (A), guanine (G), cytosine ⌐, and thymine (T). Base pairs form naturally only between A and T and between G and C so the base sequence of each single strand of DNA can be simply deduced from that of its partner strand. The code is in triplets such as ATG. The base sequence of that triplet in the partner strand is therefore TAC. The first proof that DNA is the hereditary material was provided in 1944 by Oswald Avery, Maclyn McCarty and Colin MacLoed. The double helical structure of DNA was discovered in 1953 by James D. Watson and Francis H.C. Crick with the invaluable collaboration of the X-ray crystallographer Rosalind Franklin. Watson and Crick shared the 1962 Nobel Prize in Physiology or Medicine with Maurice H.F. Wilkins.