2008年1月31日木曜日


Discovery of the DNA Double Helix
Rosalind Franklin
Rosalind Elsie Franklin (25 July 192016 April 1958) was an English physical chemist and crystallographer who made important contributions to the understanding of the fine structures of DNA, viruses, coal and graphite. Franklin is best known for her work on the X-ray diffraction images of DNA which formed a basis of Watson and Crick's hypothesis of the double helical structure of DNA in their 1953 publication, Later she led pioneering work on the tobacco mosaic and polio viruses. She died in 1958 of bronchopneumonia, secondary carcinomatosis, and cancer of the ovary.

Background

Education and Career
In the summer of 1938 Franklin went to Newnham College, Cambridge. She passed her finals in 1941, but was only awarded a decree titular, as women were not entitled to degrees (BA Cantab.) from Cambridge at the time.

University education
She worked for Ronald Norish between 1941 and 1942. Because of her desire to do war work during World War II, 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.

British Coal Utilisation Research Association
After the war ended Franklin accepted an offer to work in Paris with Jacques Mering.

Rosalind Franklin Laboratoire central des services chimiques de l'État
In January 1951, 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.

King's College London
Franklin's work in Birkbeck involved the use of x-ray crystallography to study the structure of the tobacco mosaic virus (TMV) under J. D. Bernal

Birkbeck College, London
In the summer of 1956, while on a work related trip to the United States of America (USA) Franklin first began to suspect a health problem.
She died in 1958 of bronchopneumonia, secondary carcinomatosis, and carcinoma of the ovary; her death certificate read (quote) "A Research Scientist, Spinster, Daughter of Ellis Arthur Franklin, a Banker."

Illness and death
Various controversies have surrounded Rosalind Franklin; these have all come to light after her death.

Allegations of sexism at King's College
Rosalind Franklin's contributions to the Crick and Watson model include an X-ray photograph of B-DNA (called photograph 51),

Contribution to the model of DNA
On the completion of their model, Francis Crick and James Watson had invited Maurice Wilkins to be a co-author of their paper describing the structure.

Rosalind Franklin Recognition of her contribution to the model of DNA
The rules of the Nobel Prize forbid posthumous nominations.

Nobel Prize
a) on the base:
i) "These strands unravel during cell reproduction. Genes are encoded in the sequence of bases."
ii) "The double helix model was supported by the work of Rosalind Franklin and Maurice Wilkins."
b) on the helices:
i) "The structure of DNA was discovered in 1953 by Francis Crick and James Watson while Watson lived here at Clare."
ii) "The molecule of DNA has two helical strands that are linked by base pairs Adenine - Thymine or Guanine - Cytosine."

1982, Iota Sigma Pi designated Franklin a National Honorary Member.
The U.S. National Cancer Institute awards the Rosalind E. Franklin Award for Women in Science.
The wording on the new DNA sculpture outside Clare College's Thirkill Court, Cambridge, England is Posthumous recognition

Further reading

X-ray crystallography
The Double Helix

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