25, 1953, James Watson and Francis Crick published the three-dimensional
shape of the DNA molecule in the journal Nature.
According to their model, DNA is a double-helix, composed of a pair of
sugar-phosphate backbones. Each sugar is bonded to a nitrogenous
base, either adenine, guanine, thymine, or cytosine, and each of these
is a complement for only one other, such that adenine on one nucleoside
always forms a pair of hydrogen bonds with thymine on the opposite, and
guanine forms three hydrogen bonds with cytosine in a similar manner.
This discovery would earn Watson and Crick the Nobel prize in 1962.