jimtrue.com : school : CJT2260 : 2003-10-23: DNA Video & Interactive
Posted by Jim True on October 23, 2003 6:54 AM. Last Updated October 22, 2006 9:23 PM
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Video: Rosalind Franklin and the Secret of Photo 51
Notes on Video:
DNA Detectives: Frances Krick, and American, James Watson
Rosalind Franklin, British Scientist (X-ray photograph of DNA).
Rosalind Franklin, and the secret of Photo 51
Nobel prize awarded to Krick, Watson and Wilkins.
James Watson, publishes personal account "Double Helix", depicting the race to discover the structure and introduces little known scientist, Rosalind Franklin. Watson casted Rosalind Franklin as a 'villain', hoarding her data. She died at the age of 37, so was no longer around to defend herself.
Franklin family were English jews. Rosalind stands out from an early age; enjoyed memory games. St Paul's Girl School had a strong tradition of preparing girls for careers.
Scholarship to Cambridge University for Physics and Chemistry. X-Ray Crystallography, determine hidden structure of matter. Apply math to the defraction pattern to determine structure.
1939, Cambridge appoints first Female professor and Rosalind enters a career in science.
Experiments lead to a better gas mask used during the war effort; she attained her PhD and was given a lab position in Paris.
Labortraire Central. Franklin perfected her techniques of X-Ray Diffraction. Research was not without it's risks; often checked for levels of X-Ray exposure.
King's College in London; hired by JT Randall, director of BioPhysics lab to build an X-Ray Diffraction system to determine the structure of Proteins. As she was leaving Paris, Randall asked her to shift from proteins to DNA.
1943, Oswald Avery transferred DNA from a disease causing bacteria to a harmless strain and it quickly became virulent. Showed that the virulence was transferred by DNA.
Sugar and Phosphates and 4 other ingredients called bases. Shape at that time was unknown. Determining the structure was Franklin's assignment in 1951.
Morris Wilkins fresh from the Manhattan project was the first to perform X-Ray diffraction on the structure of DNA.
King's College was very much a 'Boy's Club' atmosphere. There was great confusion over who was in charge, Morris Wilkins or Rosalind Franklin. Wilkins was on vacation and Rosalind Franklin re-designed the lab and had taken over the project. Much of this confusion was due to JT Randall's miscommunication as to who was in charge of the project. Franklin believed she was an independent researcher and Wilkins believed she was his assistant.
While Rosalind was setting up her lab at King's College, James Watson entered the game. Watson is paired with Frances Krick another physicist turned Crystallographer.
Despite the hostile environment, within months Franklin is performing remarkable results. She discovered 'two forms of DNA'. Prior to this discovery, people were looking at combinations of those two forms. The A Form is drier, more crystalline form. B is wetter and how it is formed in living cells. The X shape in the middle of the Crystalline Diffraction pattern of a helix.
Morris Wilkins was passing on Franklin's data as he felt locked out of his own experiments. X-Ray Diffraction technology is still used to determine molecular structure.
In May 1952, she created the sharpest picture yet of the B-Form, the wet DNA form, Photo 51. In the midst of this transition of her leaving King's college, someone gave Photo 51 to Wilkins. Pauling's had determined a structure for long strands of protein, a single strand of Helix.
Each twist of the helix has 10 units. They begin their model on 2/4/53. They used the information provided by Wilkins and the published findings from the MRC report that contained Franklin's data.
EAch twist of the helix has 10 units, or molecular building blocks. 34 angstroms per turn. wilkins provides this crucial information.
2 Strands each of the sugars and phosphates. But where do the bases go? Franklin said they belonged inside.
DNa always contains equal amounts of guanine and cytosine and thymine, adenine.
A - T
G - C
Arranged this way they create ladder-form within the double-helix.
Unzipping the helix creates a template for creating two new copies.
Saturday, 2/28/53. Discovered the secret of DNA and it's replication process. Franklin returned to Cambridge and reviewed the model and immediately realized it was correct.
Publications were made to Nature, placing Franklin's article at the end which implied that Franklin's article confirmed Watson's and Crick's findings. They also modified her article to include a line 'confirming the information in Watson and Crick's model'.
She went on to determine the exact geometrical structure of a virus and the disease carrying elements; worked with Aaron Klug who later received a Nobel prize.
Diagnosed with cancer at the age of 36; belief is that her work with X-Rays may have triggered the disease.
died 4/16/1958, widespread recognition for virus structures.
1962, Watson, Crick and Wilkins won Nobel Prize for discovering the structure of DNA. No mention was made of their reliance on Rosalind Franklin's assistance to their findings.
In the text, no mention is made of Rosalind Franklin. Correction, in the figure of the Chronology of DNA in Forensic Science, Franklin is listed with the discovery of the structure along with Watson, Crick and Wilkins.
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