Misplaced Pages

Rosalind Franklin: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively
← Previous editNext edit →Content deleted Content addedVisualWikitext
Revision as of 06:24, 5 January 2006 editWobble (talk | contribs)Extended confirmed users, Pending changes reviewers10,640 edits →External links← Previous edit Revision as of 06:27, 5 January 2006 edit undoWobble (talk | contribs)Extended confirmed users, Pending changes reviewers10,640 editsm →External links: format Welcome trustNext edit →
Line 115: Line 115:
* *
* in PDF format * in PDF format
*http://www.wellcome.ac.uk/en/fourplus/sci_r_franklin.html *] page.




Revision as of 06:27, 5 January 2006

Double helix

Rosalind Elsie Franklin (25 July, 1920 - 16 April, 1958) was a British physical chemist and crystallographer who made very important contributions to the understanding of the fine structures of coal and graphite, DNA and viruses. Franklin is best known for her contribution to the discovery of the structure of DNA in 1953, while working at King's College London.


Background

Rosalind Franklin was born in London into an affluent and influential Anglo-Jewish family. Her great uncle was Herbert Samuel (later Viscount Samuel) who was the first practicing Jew to serve in the British Cabinet, as Home Secretary in 1916 . He was also the first High Commissioner (effectively governor) for the British Mandate of Palestine. Her aunt Helen was married to Norman Bentwich who was Attorney General in the British Mandate of Palestine . She was educated at St Paul's Girls' School where she excelled in science and sport. Her family were actively involved in a local Working Men's College, where her father taught in the evenings. Later they helped settle Jewish refugees from Europe who had escaped the Nazis .

Cambridge and early career 1938-1950

In the autumn of 1938 Rosalind Franklin started at Newnham College, Cambridge. At this time women were not accepted as members of the University, simply as 'students of Girton and Newnham Colleges', the number of women students was kept to 500 (10% of the student body) and women were not entitled to a degree from the University. She passed her finals in 1941, and worked for R.G.W. Norish between 1941 and 1942. Because of her desire to do war work (World War II was ongoing), she worked at the British Coal Utilisation Research Association in Kingston-upon-Thames from August 1942 studying the porosity of coal. Her work helped spark the idea of high-strength carbon fibres and was the basis of her doctoral degree "The physical chemistry of solid organic colloids with special reference to coal and related materials" that she earned in 1945. After the war ended she accepted an offer to work in Paris in France with Jaques Mering. She learned x-ray diffraction techniques during her three years at the Laboratoire central des services chimiques de l'État. She seemed to have been very happy there and earned an international reputation on the structure of coal. Franklin enjoyed French culture and French conversation. She was credited by her French colleagues with speaking "perfect French with very slight English accent". In 1950 she started seeking work in England and in June 1950 she was appointed to a position at King's College London. After accepting the position at King's, but before leaving Paris, she wondered if she had made the "..biggest mistake of my life.. " .

King's College London 1951-1953

Rosalind Franklin started working as a research associate at King's College London in the Medical Research Council's (MRC) Biophysics Unit, directed by John Randall, at the beginning of January 1951. Originally to have worked on x-ray diffraction of proteins in solution, her work was redirected to DNA fibres. Maurice Wilkins was already carrying out x-ray diffraction analysis of DNA in the Unit (it was one of his photos, shown at a meeting in Naples in May 1951, which inspired James D. Watson to come to Cambridge to do similar research).

Unfortunately Randall had implied that Franklin alone would be doing X-ray work on DNA, without informing Wilkins of the decision . Maurice Wilkins was on holiday when Franklin arrived, and so he returned to find that his research project had been taken over by a newcomer. This was not a good start to a scientific relationship which went progressively downhill.

Discovery of the structure of DNA

Template:Single strand DNA discovery2 Franklin together with her Ph.D. student Raymond Gosling obtained some excellent x-ray diffraction photographs of DNA. They discovered that there were two forms of DNA, at high humidity (when wet) the DNA fibre became long and thin, when it was dried it became short and fat. These were termed DNA 'A' and 'B' respectively. The work on DNA was divided, Franklin taking the A form to study and Wilkins the 'B' form. Franklin had the better quality DNA and the better apparatus, but as would become apparent later, the B form was the form which produced the most easily interpretable x-ray diffraction pictures. The x-ray diffraction pictures taken by Franklin at this time have been called, by J. D. Bernal, "amongst the most beautiful x-ray photographs of any substance ever taken." In November 1951 King's held a colloquium on nucleic acid structure. Rosalind Franklin and Maurice Wilkins both gave presentations, James Watson was present. Shortly afterwards Francis Crick and Watson put together a model of DNA, but the flaws in the model were spotted immediately by Franklin.

By the beginning of 1952 it was generally accepted in King's that the B form of DNA was a helix and Franklin's photograph 51 seemed to put the question beyond doubt. Because of the agreement not to work on the B form, Franklin never tried to interpret the photograph. In the summer of 1952 Franklin told Randall that she was leaving King's to go to work at Birkbeck in January 1953. Gosling and Franklin were not convinced that DNA 'A' was a helical molecule. The disadvantage of working on the 'A' form of deoxyribonucleic acid is that it is a much more dense and tightly coiled molecule, which gives diffraction patterns which are more difficult to interpret. In December 1952 members of the department wrote up their work in a report for the MRC. In it, Franklin gave important information about the space group the DNA crystal fell into, 'face-centred monoclinic'. In January 1953 Maurice Wilkins showed Franklin's photograph 51 to James Watson. Crick and Watson had already obtained much information from Wilkins about the dimensions of the molecule and so started to build a new model. Crick and Watson had also managed to get hold of a copy of the MRC report from the previous December. This contained the unpublished work by Franklin on the DNA crystal's space group, and therefore was not intended to be circulated to other laboratories. Crick and Watson realised this showed that the two chains were antiparallel.

Watson and Crick succeeded in building a model of the B form of DNA incorporating the data, which was published in Nature on April 25, 1953 in an article describing the double-helical structure of DNA. Upon seeing the Crick and Watson model, Franklin is reported to have commented that it was very pretty 'but how are they going to prove it'. Crick and Watson never did prove their model. Articles by Wilkins and Franklin illuminating their x-ray diffraction data published in the same issue of Nature supported the Crick and Watson model for the B form of DNA. Francis Crick has commented that 'Strictly speaking, our model was not finally decisively proved until some 25 or so years later'. Rosalind Franklin never did work on the B form of DNA; Franklin eventually left King's College London in March 1953 to move to Birkbeck.

Rosalind Franklin and discrimination

There have been allegations that Rosalind Franklin was discriminated against because of her gender:

If Franklin was not warmly forthcoming with her findings, she cannot be altogether blamed. Female academics at King's in the 1950s were treated with a formalized disdain that dazzles modern sensibilities (actually any sensibilities). However senior or accomplished, they were not allowed into the college's senior common room but instead had to take their meals in a more utilitarian chamber that even Watson conceded was 'dingily pokey'. On top of this she was being constantly pressed — at times harassed — to share her results with a trio of men whose desperation to get a peek at them was seldom matched by more engaging qualities, like respect. "I'm afraid we always used to adopt — let's say a patronizing attitude towards her", Crick later recalled. Two of these men were from a competing institution and the third was more or less openly siding with them. It should hardly come as a surprise that she kept her results locked away.

Whereas women were not allowed into the senior common room, King's had two dining rooms, one for men, and one for men and women: Many of the men preferred to eat in the communal dining room, overlooking the Thames, and some of the scientists refused to go at all into the male preserve because of the preponderance of 'hooded crows' (clerics) . The laboratory at King's had an unusually good representation of able and responsible women scientists- about a third of the scientific staff were women. Indeed John Randall was unusual for his time for the prominence he gave to women scientists. Of thirty one members of staff, eight were women when Rosalind Franklin started working there.

There also may have been an element of class consiousness involved while Rosalind Franklin was at King's. Rosalind Franklin had attended a prestigious public school and this was evident in the way she spoke. She was seen as typically upper-class, many people really hated the upper class way of speaking . Conversely class conciousness may have influenced Rosalind Franklin's perception of King's, King's was no Oxbridge college. Its corridors echoed with something less than Received Pronunciation. To Rosalind, the voices signalled that she had got herself among the intellectually second rate.

Rosalind Franklin and DNA

Much has been written on the role that Franklin played in the discovery of the structure of DNA. Her work was an important basis for determining DNA's structure and used extensively by Crick and Watson. Franklin was very close to a solution, but had several obstacles to overcome. The antipathy between her and Maurice Wilkins was the major problem; they got off to a bad start with each other and their working relationship never recovered. This led to Franklin having no real collaborator (and so no one to trade ideas with), and to the two working in seclusion from each other, when they should have been working together. It has been implied by Wilkins himself that this situation may well have been deliberately exacerbated by John Randall. Watson has stated that Franklin "..made some wrong choices. She should have solved the structure early in 1952" (though Rosalind Franklin started to work on DNA in January 1951, just one year earlier); on the other hand, Crick has said Franklin would have made the discovery within three months, if he and Watson had not published their paper. In fact, she had already prepared a draft paper describing the structure as a double helix when Crick and Watson produced theirs. Three papers were published in the same April 1953 issue of "Nature", the first by Crick and Watson from the Cavendish Laboratory, Cambridge and two others by Gosling and Franklin, and by Stokes, Wilkins and Wilson from King's College, London.

Crick, Watson and Wilkins were awarded the 1962 Nobel Prize in Physiology or Medicine. Franklin had died of ovarian cancer on April 16, 1958 in London; which may have been caused by exposure to x-ray radiation during the course of her research. She is interred in the Willesden Jewish Cemetery in London. Some in the molecular biology community believe that since Franklin died early, and Wilkins was much less of a publicity-seeker, that Watson and Crick have in the popular mind overshadowed Wilkins and Franklin to an undeserved degree.

Research on tobacco mosaic virus

Tobacco mosaic virus was the first virus to be identified (1886). Since electron microscopy revealed that virus crystals form inside infected plants, it made sense to isolate this virus for study by x-ray crystallography. Tobacco mosaic virus was the first virus to be purified (1935). Early x-ray diffraction images for tobacco mosaic virus had been collected before World War II. In 1954 James Watson deduced that the tobacco mosaic virus had a helical structure. Franklin obtained high quality images that confirmed Watson's deduction.

Recognition

References

  1. Maddox, p.7
  2. Segev, Tom (2000): One Palestine, Complete, (ISBN 034911286X). Abacus History.
  3. Maddox, p.25
  4. Maddox, p.30
  5. Maddox, p.26
  6. Maddox, p.40
  7. Maddox, p.44
  8. Maddox, p.67
  9. Maddox, p.70
  10. Maddox, p.74
  11. Maddox, p.77
  12. Maddox, p.78
  13. Maddox, p.82
  14. Maddox, p.87
  15. Maddox, p.88
  16. "Influence of the bonding electrons on the scattering of X-rays by carbon" by R. E. Franklin in Nature (1950) volume 165 page 71. Template:Entrez Pubmed
  17. Maddox, p.92
  18. Maddox, p.108
  19. Maddox, p.111
  20. Maddox, p.115
  21. Wilkins, p.144
  22. Wilkins, p.145
  23. Wilkins, p.148
  24. Maddox, p.144
  25. "Molecular Configuration in Sodium Thymonucleate" by R. Franklin and R. G. Gosling in Nature (1953) volume 171 pages 740-741. The full text of this article is available for download in PDF format. A second article soon followed: "Evidence for 2-chain helix in crystalline structure of sodium deoxyribonucleate" by R. E. Franklin and R. G. Gosling in Nature (1953) volume 172 pages 156-157. full text PDF.
  26. Bill Bryson. A Short History of Nearly Everything. (2004), page 490. Black Swan edition 0 552 99704 8.
  27. Maddox, p. 128
  28. Wilkins, p.256
  29. Maddox, p. 133
  30. Maddox, pp. 126-127
  31. A Conversation with Jim Watson. Engineering & Science No.2 (2003) page 25. Retrieved 6 October 2005 Full text PDF.
  32. "Structure of tobacco mosaic virus" by R. E. Franklin in Nature (1955) volume 175 pages 379-81. Template:Entrez Pubmed
  33. Franklin-Wilkins Building editorial in the Pharmaceutical Journal Online Web site of The Pharmaceutical Journal (official journal of the Royal Pharmaceutical Society of Great Britain). Retrieved 7 December 2005

Bibliography

  • Chomet, S. (Ed.), D.N.A. Genesis of a Discovery, 1994, Newman- Hemisphere Press, London
  • Maddox, Brenda Rosalind Franklin: The Dark Lady of DNA, 2002. ISBN 0060184078.
  • Sayre, Anne 1975. Rosalind Franklin and DNA. New York: W.W. Norton and Company. ISBN 0393320448.
  • Wilkins, Maurice, The Third Man of the Double Helix: The Autobiography of Maurice Wilkins ISBN 0198606656.
  • Crick, FrancisWhat Mad Pursuit: A Personal View of Scientific Discovery (Basic Books reprint edition, 1990) ISBN 0465091385
  • Watson, James D., The Double Helix: A Personal Account of the Discovery of the Structure of DNA, Atheneum, 1980, ISBN 0689706022 (first published in 1968)
  • Watson, James D., Genes, Girls, and Gamow: After the Double Helix, Random House, January, 2002, hardcover, 259 pages, ISBN 0375412832
  • Krude, Torsten (Ed.) DNA Changing Science and Society: The Darwin Lectures for 2003 CUP 2003, includes a lecture by Sir Aaron Klug on Rosalind Franklin's involvement in the determination of the structure of DNA.

See also

External links

Template:Link FA

Categories: