Rosalind Elsie Franklin, an important chemist, crystallographer and pioneer in molecular biology, was instrumental in discovering the structure of DNA through X-ray diffraction techniques. Her images were the basis for James Watson's and Francis Crick's hypothesis about the double-helix structure of DNA.
Growing up in England, Rosalind Franklin attended one of the few girls' schools in London that taught physics and chemistry. She excelled at science and decided to pursue a college degree in chemistry, enrolling at Newnham College, Cambridge, in 1938 and graduating in 1941. In 1945, she earned a Ph.D. in physical chemistry from Cambridge University, where her work focused on carbon and graphite microstructures. Following the completion of her doctorate, Franklin spent four years at the Laboratoire Central des Services Chimiques de L'Etat in Paris, where she learned X-ray diffraction, a technique which determines a molecule's three-dimensional structure by analyzing the X-ray diffraction patterns of crystals that make up the molecule. Later, these techniques helped Franklin discover the structure of DNA.
In 1951, Rosalind Franklin returned to England as a research associate at John Randall's laboratory at King's College, London, where she determined that DNA had both an A and B form. Franklin also developed a method for separating the two forms, providing the first DNA crystals that were pure enough to yield interpretable diffraction patterns. When Randall assigned Franklin the task of analyzing the B form of DNA, she captured what is known as "Photograph 51" through 100 hours of X-ray exposure. This famous photograph allowed Franklin to discover basic facts about the overall structure of DNA.
Rosalind Franklin's discoveries also refuted some common misconceptions about DNA. For example, she learned that the location of DNA's sugar-phosphate backbone was on the outside of the molecule, and not on the inside as previously thought. Additionally, she discovered that the helical structure of DNA had two strands, and not three as was commonly presumed. The missing piece of the puzzle was how the bases paired on the inside of the helix, but James Watson and Francis Crick would eventually solve this mystery. In 1953, Watson and Crick published their now-famous scientific paper, using Photograph 51 as the basis for their famous model of DNA, and citing Franklin as a source.
Rosalind Franklin refocused her research soon after Watson's and Crick's paper was published, completing work on both the tobacco mouse virus and the polio virus, and laying the foundation for modern virology. In 1962, Watson, Crick and Franklin's colleague, Maurice Wilkins, were awarded the Nobel Prize for their discovery of the structure of DNA. Because Nobel Prizes are not awarded posthumously, however, Franklin, who had died four years earlier from ovarian cancer at the age of 37, was not honored along with her colleagues. Nevertheless, Franklin's measurable contributions to understanding the structure of DNA provided much of the foundation for modern genetics.
Resources:
http://www.sdsc.edu/ScienceWomen/franklin.html
http://www.accessexcellence.org/RC/AB/BC/Rosalind_Franklin.html
http://www.lifeindiscovery.com/whyrosalindfranklin/index.html
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Re: Woman of the Week - Rosalind Elsie Franklin (July 25, 1920 – April 16, 1958)