“The instant I saw the picture my mouth fell open and my pulse began to race.” So wrote James Watson in The Double Helix, his controversial account of discovering DNA’s structure in 1953. The image, photograph 51, showed a helical pattern from x-rays diffracted from DNA strands. Rosalind Franklin, an x-ray crystallographer at King’s College London, produced it in 1952. Watson’s 1968 book implied the insight was his alone, and popular accounts still suggest Franklin missed its significance. She died of cancer in 1958, before his memoir became a bestseller.
A new analysis of Franklin’s notes on another x-ray image, photograph 49, offers a firm rebuttal. Science historian Alistair Sponsel of the Science History Institute and crystallographer Brian Sutton of KCL argue Franklin knew the earlier photo revealed a helix—the epiphany Watson claimed—and that is why she made the more refined photograph 51. Her notes on photograph 49 calculated the length of each turn in the spiral—34 angstroms—and the number of bases “per turn of helix.”
The new paper does not challenge Watson and Crick’s achievement. Their model of DNA, with two strands running in opposite directions and complementary base pairs, went beyond Franklin’s understanding. But Sponsel and Sutton found answers by going back to her lab books at the University of Cambridge and her photography equipment at KCL, showing Franklin “knows exactly what’s in front of her,” says Betty Smocovitis.
Source: Hacker News · Summarized by HeadlinesBriefing