Crick was born in Northampton, UK, in 1916. He received a degree in physics from University College London in 1937 but had his PhD research cut short by the outbreak of the Second World War. During the war he worked as a scientist for the British Admiralty and in 1947 joined Cambridge University to carry out research on biology.

After two years at the Strangeways Laboratory, he joined a team at the Cavendish physics laboratory headed by Max Perutz that was using X-ray diffraction to study protein structure. Then in 1951 he met the young American scientist James Watson, and two years later the pair published a short letter in Nature describing the structure of the DNA molecule. This work drew on X-ray diffraction data obtained by Rosalind Franklin and Maurice Wilkins at King's College London.

Crick and Watson discovered that DNA is structured in two helical strands coiled around the same axis and held together by pairs of the four DNA bases -- adenine, guanine, thymine and cytosine. They realized that adenine always pairs with thymine and guanine is always linked with cytosine, which means that the ordering of the bases can be reproduced and that strands of DNA can therefore replicate themselves.

In contrast to Crick's reputation for being upfront and abrasive, the opening two lines of the Nature paper were distinctly understated. "We wish to suggest a structure for the salt of deoxyribose nucleic acid (DNA)," wrote Crick and Watson. "This structure has novel features which are of considerable biological interest."

Lord May, president of the Royal Society, says that "Francis Crick made an enormous contribution to science and his discoveries helped to usher in a golden age of molecular biology. His death is a sad loss to science."

Following his ground-breaking discovery, Crick spent the next 13 years working with Sydney Brenner on understanding how the sequence of base pairs within a DNA molecule is used to determine protein structure. In 1977 Crick moved to the Salk Institute in San Diego to work in the field of neurobiology, attempting to produce a scientific understanding of consciousness.