Discovering 'the secret of life' - 70th anniversary of DNA double helix breakthrough

Francis Crick's announcement to patrons of The Eagle pub that he and James Watson had "discovered the secret of life", the evening after their determination of the structure of the DNA molecule, has become a part of Cambridge folklore.

Their breakthrough - pinpointing how our genetic code is passed from parent to child - has led to world-changing advances in many fields, not least in biological research and our understanding and treatment of inherited diseases. But the discovery, which was made at Cambridge's Cavendish Laboratory 70 years ago, was only possible because of the work of a host of talented scientists.

Lawrence Bragg's appointment as Cavendish Professor of Physics in 1938 - succeeding Ernest Rutherford - was key. Along with his father William, Bragg had already won a Nobel Prize in 1915, after discovering that X-rays could be used to determine the positions of atoms within a crystal.

"Bragg was a hugely important figure in this," said Professor Malcolm Longair, Director of Development at the Cavendish Laboratory.

"When he became Cavendish professor it was quite a shock to the community here, because he was a crystallographer rather than a nuclear physicist, which the laboratory was famous for. He encouraged the X-ray crystallography of biological substances as soon as he came to Cambridge."

Bragg's interest was bolstered by the remarkable X-ray crystallography data on haemoglobin, obtained by Max Perutz.

Following the Second World War, Bragg continued to support crystallography at Cambridge, encouraging Perutz and John Kendrew in their efforts to determine the structure of haemoglobin and myoglobin. Also working in X-ray crystallography at the time, and one of very few women at the Cavendish Laboratory, was June Broomhead. Her work measuring the dimensions of adenine and thymine molecules would be crucial to cracking the mystery of DNA's structure, as would her colleague Bill Cochran's theoretical research that explained the detailed images produced by a single helix.

"These are the people, and there are others besides, who formed the core of this experimental work," said Prof Longair. "They were all contributing very significantly to how you analyse the data.

"A significant point is that Watson and Crick were both theorists, they didn't do any of the experiments that resulted in the X-ray crystallography images, which they set about interpreting. There were lots of people who contributed to the knowledge of the size of the molecules that had to be fitted together, as they eventually were. They were working in one of the best places they could be to study the crystallographic work."

Public link

Please use the above public link if you want to share this noodl on another website.