Franklin's X-Ray Crystallography Experiments
Regular substances like crystals diffract X-rays in characteristic patterns according to their physical structure. The X-ray crytallograph at right shows the diffraction pattern of a crystallized DNA molecule. The cross pattern in the middle is characteristic of a helical molecule with regular repeats; the broad bands at top and bottom give an indication of the periodicity of the repeats. The photograph is of the highly hydrated B form of DNA, rather than the A form, which does not show a distinct helical structure.
(1920-1958), whose grad student Raymond Gosling (1926 - )
made the photograph, worked as a post-doctoral
researcher in the lab of Maurice
and approached the structure of DNA as a physical
structure. Opinion and evidence vary as to how and when she
evidence as bearing on the helical nature of the molecule.
was given the photo by Gosling, and showed it
to Watson, who immediately realized its implications. Watson,
subsequently received the Nobel Prize in 1962 for solving
of DNA. By the time of the award, Franklin was dead: the
not awarded posthumously, nor to more than three persons.
Watson's autobiographic account of the discovery of "The Double Helix" (1968)
unflattering personal portrait of Franklin, and was widely
as inaccurate and sexist. Anne
Sayre's biography, "Rosalind
and DNA" (1975) discusses the challenges faced by women
science. Watson and Crick repeatedly acknowledged that
they could not
have solved the structure without Franklin's evidence.