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|The story of DNA|
The greatest scientific discovery of the century
One lunchtime in March 1953, a young scientist called Francis Crick rushed into his local pub in Cambridge and triumphantly declared that he and his colleague, James Watson, had just discovered ‘the secret of life’. The breakthrough the two had made was, indeed, extraordinary, for they had worked out the molecular structure of DNA - the chemical substance found in the nucleus of every living cell. The double helix structure they had deduced revealed that DNA could do two crucial things - it could carry information and it could carry information and it could replicate itself. It was a discovery that would revolutionise biology.
By the early 1950s, scientists had already identified DNA as the molecule that carried the biochemical information that enables all living things to exist, and so a race was on to discover exactly how it did this. Also close to solving the puzzle were the New Zealander Maurice Wilkins and Rosalind Franklin, who were both working on X-ray pictures of DNA at King’s College, London, and the great American physical chemist Linus Pauling.
Crick and Watson met in 1951 at the Medical Research Council’s Cavendish Laboratory in Cambridge, where Crick, then 35, was working on a study of haemoglobin crystals, and Watson, an American and 12 years his junior, had just arrived from America to work on another project. The two shared an office and discovered not only that they shared a fascination with DNA but that they were both intrigued by Linus Paulin’s theories.
Deciding that they needed clearer X-ray pictures of the molecule, they made contact with Franklin and Wilkins at King’s College, and Watson then attended a conference at which Rosalind Franklin described her X-ray results. Using the information he brought back, he and Crick produced their first model structure, which they invited Rosalind Franklin to view. But she was unimpressed, because the model was inconsistent with her results - which Watson had in fact misunderstood.
Realising their first attempt was flawed, Crick and Watson temporarily stepped back from the problem. But then some crucial findings (about DNA’s chemical base pairs A/T and G/C) by the Austrian-American biochemist Edwin Chargaff, and a clearly erroneous paper by Pauling, rekindled their determination. Watson once again visited King’s where Wilkins showed him more of Franklin’s photographs, and these, together with an official report on Franklin’s data, gave them the missing pieces of the puzzle.
Using laboratory clamps and pieces of metal, they set about building a giant model of a section of DNA, which is now displayed in the London Science Museum. And in April 1953, Nature magazine published their paper ‘A structure for Deoxyrilbose Nucleic Acids’. This was accompanied by paper from the Wilkins and Franklin group at King’s, and contained now the famous understatement: ‘It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.’
Rosalind Franklin sadly died in 1958, but in 1962 Watson, Crick and Wilkins were awarded the Nobel Prize for Physiology or Medicine ‘for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material.’
The text is from DNA and after: 50 years of UK excellence, Foreign & Commonwealth Office London and British Council, 2003, p 6-7.
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