Tag Archives: structure of dna

WHAT IS: Photo 51


 
 

Photo 51, showing x-ray diffraction pattern of DNA

Photo 51 is the nickname given to an X-ray diffraction image of DNA taken by Raymond Gosling in May 1952, working as a PhD student under the supervision of Rosalind Franklin,[1][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 without Rosalind Franklin’s approval or knowledge 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][6] 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][9][10]

Photo 51 became a crucial data source[11] 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.

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Today’s Birthday: FRANCIS HARRY COMPTON CRICK (1916)


Francis Harry Compton Crick (1916)

While working in a research lab at Cambridge after WWII, Crick helped discover the molecular structure of DNA. It was one of the most important scientific findings of the century, and he shared the 1962 Nobel Prize in Physiology or Medicine for his work. He also clarified how cells use DNA to build proteins. During WWII, he was deflected from his original course of research after a bomb hit his lab. Crick later said he had been studying “the dullest problem imaginable” at the time. What was it? More… Discuss