How Rosalind Franklin Proved The Shape of DNA

27 Jul

Google celebrates Roslind Franklin

The Google Doodle Celebrates the Life and Discoveries of Rosalind Franklin: The First Person to Photograph DNA’s StructureRosalind Franklin young photo

On Thursday, July 25th, you may have noticed Google’s homepage altered to celebrate one of the key discoveries in science: the discovery of the structure of DNA. But their doodle didn’t refer to the usual men celebrated for its discovery – instead it acknowledged an often overlooked woman.

Most of the recognition for the discovery, including the Nobel prize, went to James Watson and Francis Crick, but few were aware at the time that their theory hung on the work of a young woman named Rosalind Franklin.

The Race to Discover the Secret Shape of Life

In the early 1950’s a race was on in academia to discover where human genetic material was organized in the body.  A scientist named Maurice Wilkins believed it was hidden within the structure of DNA, which inspired Waston and Crick to search for the exact shape of the molecule.

Watson and Crick knew they were competing with the greatest mind in science at the time, Linus Pauling, who was already close to  proposing a model for DNA.  They decided to skip the rigorous proofs, in what Watson refered to in his Ted Talk (VIDEO below) as a short cut, and simply come up with a model based on coordinates from x-ray photographs.

“Good artists copy, great artists steal!” – Pablo Picasso

To study the structure of DNA, Wilkins worked with a young X-ray crystallographer at King’s College in London named Rosalind Franklin.  Franklin was a brilliant x-ray crystallographer who was the first scientist to present several important pieces of information essential to the structure of DNA, including two forms of DNA, type A and type B forms.  Her work formed much of the basis for Watson and Crick’s Nobel Prize winning model.

They didn’t give her a Nobel Prize, but they did say “thanks”… eventually.

How She Did It:

Franklin used the newest methods at the time of photographing molecules in order to understand their structure, which essentially gave Watson and Crick their “shortcut”.  First photo of DNA structure

X-Ray Crystallography uses the diffraction of x-rays in order to calculate the positions of atoms within a molecule.   First you turn the molecule into a crystal.  Then you hit the crystal with x-rays.  Then you measure the angles of diffraction of the x-rays.  Then you turn those calculations into a 3D model of the density of electrons in the crystal.  Then someone with a really big brain uses the electron densities to calculate the positions of the atoms and their bonds with other atoms in the structure.

But just looking at the picture is a lot simpler.  See the double helix?

Wilkins & Franklin Vs. Watson & Crick

Wilkins and Franklin at the time were undertaking a vigorous study of the molecule in order to get undeniable proof of the structure of DNA.  Watson and Crick, on the other hand, were building models in an attempt to find their shortcut to publishing the right answer before anybody else did.

Initially, Watson and Crick built a model of a three stranded DNA molecule, which they showed to Wilkins and Franklin.  Rosalind Franklin apparently laughed at their attempt.  They were told to stop building models because they were so wrong. They were so embarrassed, they actually stopped.

(Ironically, their biggest threat in the DNA race, Linus Pauling, later also proposed a three stranded model. This means Rosalind Franklin would have laughed at him too.)

They might have stopped for good, and have been scooped by someone else in the DNA race, if Rosalind hadn’t moved to another college.  Once she moved, Wilkins told them to go back to model building, and with Franklin’s photographs as their basis (which Wilkins showed to Watson and Crick without Franklin’s permission as she was moving away), they were able to build a working model of DNA as a double helix.

The Rest is History

Watson and Crick published their findings in the journal Nature in 1953, with the briefest of mentions that they had been made aware of the as of yet unpublished work of Ms. Franklin.

They spent the next 7 years proving that their model was correct, and eventually were awarded, along with Wilkins, the Nobel Prize in 1962.

Rosalind Franklin died of cancer, possibly from overexposure to X-rays, in 1958.

Rosalind Franklin photographs DNA

Today, Rosalind Franklin is known as a major contributor to Watson and Crick’s double helix model.  She has been awarded over a dozen posthumous recognitions, and now… she has her own Google Doodle.

Girl Power indeed.



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One Response to “How Rosalind Franklin Proved The Shape of DNA”

  1. judi bola August 1, 2013 at 8:29 am #

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