The Double Helix

Although controversy continues to cloud the assignment of credit more than six decades after the 1953 discovery of the structure of deoxyribonucleic acid (DNA), no question exists regarding its cardinal significance in the transference of hereditary information, nor that is it one of the greatest scientific discoveries. In 1950, the basic elements of DNA’s structure were known to consist of nitrogenous bases—adenine, cytosine, guanine, and thymine—a sugar, and a phosphate group, but the nature of the linkage among the components remained obscure. Competition for this discovery focused upon Linus Pauling at California Institute of Technology and the James Watson and Francis Crick team at the Cambridge University’s Cavendish Laboratory.

Pauling, considered among the most important scientists of the twentieth century and who, in coming years, was to be the recipient of two Nobel Prizes, proposed that DNA was a triple helix—a model based upon a number of fundamental errors that led him astray. Early in 1953, Watson and Crick focused their attention on a two-chain model, with each long chain twisted about the other and traveling in opposite directions—a double helix—and with alternating sugar and phosphate groups. Their model was supported by X-ray diffraction photographic images made by Maurice Wilkins and Rosalind Franklin at King’s College London. On April 25, 1953, the Watson-Crick paper appeared in Nature magazine, with only a terse footnote referring to Franklin’s and Wilkins’s “unpublished contribution.”

This double-helix access ramp of a seven-level underground parking garage in Nantes, France, echoes the structure of DNA.

Prior to submission of the Nature paper, without her permission or knowledge, copies of Franklin’s outstanding photographs were shared with Watson, and one in particular was considered by many to be pivotal in the discovery of the double helix. The relative significance and importance of Franklin’s contribution has not been resolved. But what appears incontrovertible is that she was never formally recognized during her lifetime and, when the Nobel Prize was awarded in 1962, she had never been nominated nor even acknowledged by Watson, Crick, or Wilkins, the recipients. (Pauling received the Nobel Peace Prize that same year.) Franklin died at the age of 37 of ovarian cancer in 1957, and deceased individuals are ineligible for the Nobel Prize.