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Thứ Năm, 25 tháng 7, 2013

Rosalind Franklin, "the woman who was not awarded the Nobel prize for the co-discovery of the structure of DNA".

Rosalind Franklin, DNA scientist, celebrated by Google doodle from guardian.co.uk,

British biophysicist and x-ray crystallographer helped discover DNA's structure but controversially missed out on Nobel prize


Thursday 25 July 2013 01.24 BST

The Google doodle dedicated to Rosalind Franklin. Photograph: Screen grab



The latest Google doodle celebrates the life and work of British biophysicist and x-ray crystallographer Rosalind Franklin, whose research led to the discovery of the structure of DNA.
Franklin was born in Notting Hill, London on 25 July 1920.
The second "o" in the doodle contains her image, while the "l" has been replaced with the DNA double helix.

Franklin also made critical contributions to our understanding of the molecular structures of RNA, viruses, coal and graphite.

She died from ovarian cancer in April 1958, aged just 37.

The scientist has perhaps become best known as "the woman who was not awarded the Nobel prize for the co-discovery of the structure of DNA".

During her DNA research, Franklin worked at King's College London under Maurice Wilkins.

The story goes that he took some of her x-ray crystallography images without her knowledge and showed them to his friends, Francis Crick and James Watson, who were also trying to discover the structure of DNA.

Wilkins, Crick and Watson were awarded the Nobel prize in Chemistry in 1962.

Crick later acknowledged that Franklin's images were "the data we actually used" to formulate their 1953 hypothesis regarding the structure of DNA.

The most significant of those images is known as Photo 51, which is also the inspiration for an exhibition currently at Somerset House in London.
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Photo 51 is the nickname given to an X-ray diffraction image of DNA taken by Raymond Gosling in May 1952 [1] under the direction of Rosalind Franklin[2][3][4] at King's College London in Sir John Randall's group. It was critical evidence [5] in identifying the structure of DNA. [6]
James Watson was shown the photo by Maurice Wilkins, and along with Francis Crick, Watson used characteristics and features of Photo 51 to develop the chemical model of DNA molecule. In 1962, the Nobel Prize in Physiology or Medicine was awarded to Watson, Crick and Wilkins. The prize was not awarded to Franklin; she had died 4 years earlier, making her ineligible for nomination. [7]
The photograph provided key information that was essential for developing a model of DNA.[8][9] The diffraction pattern determined the helical nature of the double helix strands (antiparallel). The outside linings of DNA have a phosphate backbone, and codes for inheritance are inside the helix. Watson and Crick's calculations from Franklin's photography gave crucial parameters for the size and structure of the helix. [8][10][11]
Photo 51 became a crucial data source[12] that led to the development of the DNA model and confirmed the prior postulated double helical structure of DNA, which were presented in the articles in the Nature journal by Raymond Gosling.




As historians of science have re-examined the period during which this image was obtained, considerable controversy has arisen over both the significance of the contribution of this image to the work of Watson and Crick, as well as the methods by which they obtained the image. Franklin was hired independently of Maurice Wilkins, who, nonetheless, showed Photo 51 to Watson and Crick, without her knowledge. Whether Franklin would have deduced the structure of DNA on her own, from her own data, had Watson and Crick not obtained her image, is a hotly debated topic,[13][14][15] made more controversial by the negative caricature of Franklin presented in Watson's history of the research on DNA structure, The Double Helix.[13][16][17] Watson later admitted his distortion of Franklin in his book, noting in a preface to a later edition: "Since my initial impressions about [Franklin], both scientific and personal (as recorded in the early pages of this book) were often wrong, I want to say something here about her achievements." 
[From Wikipedia]
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Rosalind Franklin biography

Born On This Day
Rosalind Franklin was born on this day in 1920.

 

Quick Facts

  • NAME: Rosalind Franklin
  • OCCUPATION:Chemist
  • BIRTH DATE:July 25, 1920
  • DEATH DATE:April 16, 1958
  • EDUCATION: Newnham College, Cambridge University
  • PLACE OF BIRTH: London, England
  • PLACE OF DEATH: London, England
  • Full Name: Rosalind Elsie Franklin
  • AKA: Rosalind Franklin

Best Known For

British chemist Rosalind Franklin is best known for her role in the discovery of the structure of DNA ,and for her pioneering use of X-ray diffraction.




Born in 1920 in London, Rosalind Franklin earned a Ph.D. in physical chemistry from Cambridge University. She learned crystallography and X-ray diffraction, techniques that she applied to DNA fibers. One of her photographs provided key insights into DNA structure. Other scientists used it as the basis for their DNA model and took credit for the discovery. Franklin died of ovarian cancer in 1958, at age 37.


British chemist Rosalind Elsie Franklin was born into an affluent and influential Jewish family on July 25, 1920, in Notting Hill, London, England. She displayed exceptional intelligence from early childhood, knowing from the age of 15 that she wanted to be a scientist. She received her education at several schools, including North London Collegiate School, where she excelled in science, among other things.

Rosalind Franklin enrolled at Newnham College, Cambridge, in 1938 and studied chemistry. In 1941, she was awarded Second Class Honors in her finals, which, at that time, was accepted as a bachelor's degree in the qualifications for employment. She went on to work as an assistant research officer at the British Coal Utilisation Research Association, where she studied the porosity of coal—work that was the basis of her 1945 Ph.D. thesis "The physical chemistry of solid organic colloids with special reference to coal."

In the fall of 1946, Franklin was appointed at the Laboratoire Central des Services Chimiques de l'Etat in Paris, where she worked with crystallographer Jacques Mering. He taught her X-ray diffraction, which would largely play into her discovery of "the secret of life"—the structure of DNA. In addition, Franklin pioneered the use of X-rays to create images of crystalized solids in analyzing complex, unorganized matter, not just single crystals.


In January 1951, Franklin began working as a research associate at the King's College London in the biophysics unit, where director John Randall used her expertise and X-ray diffraction techniques (mostly of proteins and lipids in solution) on DNA fibers. Studying DNA structure with X-ray diffraction, Franklin and her student Raymond Gosling made an amazing discovery: They took pictures of DNA and discovered that there were two forms of it, a dry "A" form and a wet "B" form. One of their X-ray diffraction pictures of the "B" form of DNA, known as Photograph 51, became famous as critical evidence in identifying the structure of DNA. The photo was acquired through 100 hours of X-ray exposure from a machine Franklin herself had refined.

John Desmond Bernal, one of the United Kingdom’s most well-known and controversial scientists and a pioneer in X-ray crystallography, spoke highly of Franklin around the time of her death in 1958. "As a scientist Miss Franklin was distinguished by extreme clarity and perfection in everything she undertook," he said. "Her photographs were among the most beautiful X-ray photographs of any substance ever taken. Their excellence was the fruit of extreme care in preparation and mounting of the specimens as well as in the taking of the photographs."

 
Despite her cautious and diligent work ethic, Franklin had a personality conflict with colleague Maurice Wilkins, one that would end up costing her greatly. In January 1953, Wilkins changed the course of DNA history by disclosing without Franklin's permission or knowledge her Photo 51 to competing scientist James Watson, who was working on his own DNA model with Francis Crick at Cambridge.

Upon seeing the photograph, Watson said,

"My jaw fell open and my pulse began to race," according to author Brenda Maddox, who in 2002 wrote a book about Franklin titled Rosalind Franklin: The Dark Lady of DNA.

The two scientists did in fact use what they saw in Photo 51 as the basis for their famous model of DNA, which they published on March 7, 1953, and for which they received a Nobel Prize in 1962. Crick and Watson were also able to take most of the credit for the finding: When publishing their model in Nature magazine in April 1953, they included a footnote acknowledging that they were "stimulated by a general knowledge" of Franklin's and Wilkins' unpublished contribution, when in fact, much of their work was rooted in Franklin's photo and findings. Randall and the Cambridge laboratory director came to an agreement, and both Wilkins' and Franklin's articles were published second and third in the same issue of Nature. Still, it appeared that their articles were merely supporting Crick and Watson's.

According to Maddox, Franklin didn't know that these men based their Nature article on her research, and she didn't complain either, likely as a result of her upbringing. Franklin "didn't do anything that would invite criticism … [that was] bred into her," Maddox was quoted as saying in an October 2002 NPR interview.

Franklin left King's College in March 1953 and relocated to Birkbeck College, where she studied the structure of the tobacco mosaic virus and the structure of RNA. Because Randall let Franklin leave on the condition that she would not work on DNA, she turned her attention back to studies of coal. In five years, Franklin published 17 papers on viruses, and her group laid the foundations for structural virology.


In the fall of 1956, Franklin discovered that she had ovarian cancer. She continued working throughout the following two years, despite having three operations and experimental chemotherapy. She experienced a 10-month remission and worked up until several weeks before her death on April 16, 1958, at the age of 37.

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