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Accumulating Glitches. Saltwater Science. Microbe Matters. You have authorized LearnCasting of your reading list in Scitable. Do you want to LearnCast this session? This article has been posted to your Facebook page via Scitable LearnCast. In , Franklin was offered a 3-year research scholarship at King's College in London. With her knowledge, Franklin was to set up and improve the X-ray crystallography unit at King's College. Franklin arrived while Wilkins was away and on his return, Wilkins assumed that she was hired to be his assistant.
It was a bad start to a relationship that never got any better. Working with a student, Raymond Gosling, Franklin was able to get two sets of high-resolution photos of crystallized DNA fibers. She used two different fibers of DNA, one more highly hydrated than the other. From this she deduced the basic dimensions of DNA strands, and that the phosphates were on the outside of what was probably a helical structure.
She presented her data at a lecture in King's College at which James Watson was in attendance. In his book The Double Helix , Watson admitted to not paying attention at Franklin's talk and not being able to fully describe the lecture and the results to Francis Crick. Franklin did not know Watson and Crick as well as Wilkins did and never truly collaborated with them. Franklin left Cambridge in and went to the Birkbeck lab to work on the structure of tobacco mosaic virus.
She published a number of papers on the subject and she actually did a lot of the work while suffering from cancer. Science, for me, gives a partial explanation of life. In so far as it goes, it is based on fact, experience and experiment.
In late February , Rosalind Franklin, a year-old physical chemist working in the biophysics unit of King's College in London, wrote in her notebooks that the structure of DNA had two chains. She had already worked out that the molecule had its phosphate groups on the outside and that DNA existed in two forms. They did it not only through brilliant intuition and a meeting of compatible minds, but also on the basis of Franklin's unpublished experimental evidence, which had reached them through irregular routes.
She did not know that they had seen either her X-ray photograph Fig. Bernal, For that matter, no one at King's realized they were in our hands. By then Franklin had died — in , at the age of 37, from ovarian cancer. Such flamboyantly chauvinist phrases were sufficient to launch the legend of Franklin, the wronged heroine.
So too was Watson's insistence on judging Franklin by her appearance rather than by her performance as a scientist. She was, when she came to King's from the French government laboratory where she had worked from to the end of , a recognized expert on the structure of coals, carbons and disordered crystals, with many publications to her credit.
The Franklin myth has continued to grow, abetted by the fact of her tragically early death. Franklin has become a feminist icon — the Sylvia Plath of molecular biology — seen as a genius whose gifts were sacrificed to the greater glory of the male.
Her failure to win the Nobel prize has been given as a prime example of the entrenched misogyny of the science establishment, rather than the consequence of the Nobel statute against posthumous awards.
Sayre's book provided a much-needed corrective portrait, but was marred by a feminist bias. For example, it grossly underestimated the number of women scientists at King's in the early s. Sayre maintained there was only one other than Franklin, whereas there were at least eight on the senior staff.
She insisted, moreover, that women's exclusion from the King's senior common room deprived Franklin of the intellectual companionship of her colleagues.
In fact, most of the scientific staff preferred to eat in the joint dining room, men and women together, and the women, in general, felt well treated at King's. As a biographer writing nearly three decades later and given access to Franklin's personal correspondence, I found a more attractive, capable woman than Watson had suggested, and a King's College more congenial and welcoming to women scientists than Sayre had allowed.
I also found that Franklin felt singularly unhappy at King's, not so much because of her gender, but because of her class and religion: a wealthy Anglo-Jew felt out of place in a Church of England setting dominated by swirling cassocks and students studying for the priesthood.
She was, in fact, so unhappy at King's that, in early , getting out as fast as possible was far more important to her than finishing her work on DNA. How far she had advanced was reported in two articles in Nature 3 , 4 by Sir Aaron Klug, Franklin's closest collaborator at Birkbeck College, London, where she moved to from King's.
He concluded that she had come very close to discovering the structure of DNA herself. However, at that time scientists generally agreed that DNA merely provided structural support for cells and that protein must be genetic material. When mounting the DNA fibers for viewing, Wilkins and Gosling were able to bundle many of the thin fibers together and pull them tight to provide a larger sample to better diffract X-rays. Furthermore, the two researchers kept the DNA fibers wet with water by keeping them in a humid environment.
The resulting X-ray diffraction pattern of DNA was of a higher quality than any patterns collected prior. Before joining the lab, Franklin conducted X-ray diffraction experiments on carbon compounds at a government lab in Paris, France, and published several papers on X-ray crystallography of coal and coal compounds.
By improving her methods of collecting DNA X-ray diffraction images, Franklin obtained Photo 51 from an X-ray crystallography experiment she conducted on 6 May First, she minimized how much the X-rays scattered off the air surrounding the crystal by pumping hydrogen gas around the crystal. Because hydrogen only has one electron, it does not scatter X-rays well. She pumped hydrogen gas through a salt solution to maintain the targeted hydration of the DNA fibers.
Franklin tuned the salt concentration of the solution and the humidity surrounding the crystal to keep DNA entirely in the B-Form. After exposing the DNA fibers to X-rays for a total of sixty-two hours, Franklin collected the resulting diffraction pattern and labeled it Number 51 that became Photo The outermost edge of the diffraction pattern consists of a black diamond shape. The diamond has rounded corners with the darkest corners situated at the top and bottom of the film. The diamond shape of the DNA diffraction pattern is not made of fine, definite lines, but rather thick, fuzzy boarders that vary in darkness such that the boarders fade on the left and right hand sides of the film.
Inside the diamond is a cross shape like the letter "X. Instead, along each line of the X are four horizontal dashes, called spots that become darker moving closer to the center of the film. There is a hole at the center of the film, with dark spots lining the outside of the center hole.
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