Watson and Crick?

Question

What data was existent at the time Watson and Crick came up with their model for the structure of DNA? What did they base their hypothesis on?

Answer 1

Watson and Crick used X ray diffraction data produced by Rosalin Franklin, who was then in the lab of Maurice Wilkins.  Wilkins had a habit of showing Franklin's data to Watson and Crick, who then used that data to produce their double helix model.  Today, this would never be done without the permission of the person who generated the data, but Franklin was a rare women in a very male-dominated profession.   Franklin died a couple of years later of cancer, probably from exposure to all of those X rays, and so was left off of the Nobel prize when it was awarded to Wilkins, Watson and Crick in 1953.

Answer 2

1.The X-ray diffraction pictures of Rosalind Franklin,Ray Gosling and Maurice Wilkins at King's College London.

2.Alpha helix studies of Francis Crick and Bill Cochrane's (Cambridge) work on the theory of the alpha hekix in proteins.

3.Erwin Chargaff's base pairing rules - A&T;G&C.

4.Jerry Donohue's (Cambridge) analysis that the bases were in the keto form and not the enol form and so would fit.

Answer 3

If memory serves, the width of a DNA molecule was known by X-ray analysis.  Further, Linus Pauling had published on the alpha helix in protein.

Watson and Crick borrowed heavily from X-ray data from Rosalind Franklin.  Their major breakthrough was the recognition of base pairing between nucleotides.

Answer 4

Watson and Crick basically tricked Rosyln Franklin into showing them a very key bit of data; an X ray crystollograph of DNA, which suggested that DNA assumed a helical structure.  They also used base pairing rules of Chargoff, and knowledge that DNA is comprised of nucleotides hooked together via phosphodiester bonds to elucidate a final structural model.  But it was Franklin's data that was key.

We now actually know that the "Watson-Crick" model is not the primary structure actually assumed by DNA, but it is close.  Basically, Watson and Crick solved that structure without generating any data of their own; they, as Jeff Goldblum (who played Watson in "the Race for the Double Helix) said in Jurassic Park; "...stood on the backs of giants".  Rosyln Franklin, who it is widely believed would have solved the structure herself had she not died, did not even share the Nobel Prize with Watson and Crick.

Answer 5

At the time of Watson and Crick, one of the important scientific findings was Chargraff's rule that stated that the each purine was paired with a pyrimidine.  This was the basis of the stability of double stranded DNA, but the reason was not known until Watson and Crick showed the three dimensional structure of the DNA.

Their picture of the structure of DNA came from X-ray crystallography of DNA.