Watson, James Dewey (born 1928), American molecular biologist. Watson is famous for his major role in the discovery of the molecular structure of DNA. In 1951 he began working with Francis Crick at Cambridge, England, learning X-ray diffraction techniques and studying the problem of DNA structure. In 1953 he realized that the essential DNA components—four organic bases—must be linked in definite pairs. This discovery was the key factor that enabled Watson and Crick to formulate a molecular model for DNA in which the organic base pairs are linked by hydrogen bonds to form the rungs of a flexible ladder spiraling in the form of a helix. In this model, DNA replicates itself by splitting lengthwise and reconstructing a double strand of DNA from each of the single strands. This was a major stepping-stone in understanding the process by which genetic material replicates.
Crick, Francis Harry Compton (1916–2004), British molecular biologist. Crick had a major role in the determination of the molecular structure of DNA, a discovery which is widely regarded as one of the most important of 20th-century biology. He joined the research staff at Cavendish Laboratories in Cambridge, England. By 1961 Crick demonstrated that each group of three bases on a single DNA strand designates the position of a specific amino acid on the polypeptide chain of a protein molecule. He also helped to determine the base triplets that code for each of the 20 amino acids normally found in proteins. Watson, Crick, and Maurice Wilkins were awarded the Nobel Prize for Physiology or Medicine in 1962.