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1952: an X-ray diffraction image of DNA was taken by Raymond Gosling in May 1952, a student supervised by Rosalind Franklin. [30] 1953: DNA structure is resolved to be a double helix by James Watson, Francis Crick and Maurice Wilkins. [31] 1955: Alexander R. Todd determined the chemical makeup of nitrogenous bases.
In April 2023, scientists, based on new evidence, concluded that Rosalind Franklin was a contributor and "equal player" in the discovery process of DNA, rather than otherwise, as may have been presented subsequently after the time of the discovery. [7] [8] [9]
In the 1940s and early 1950s, experiments pointed to DNA as the portion of chromosomes (and perhaps other nucleoproteins) that held genes. A focus on new model organisms such as viruses and bacteria, along with the discovery of the double helical structure of DNA in 1953, marked the transition to the era of molecular genetics.
DNA contains the genetic information that allows all forms of life to function, grow and reproduce. However, it is unclear how long in the 4-billion-year history of life DNA has performed this function, as it has been proposed that the earliest forms of life may have used RNA as their genetic material.
1869 – Friedrich Miescher identifies DNA in the sperm of a trout. 1871 – Felix Hoppe-Seyler discovers invertase, which is still used for making artificial sweeteners. 1877 – Robert Koch develops a technique for staining bacteria for identification. 1878 – Walther Flemming discovers chromatin leading to the discovery of chromosomes.
The advances in genetic engineering. [3] Herb Boyer studied bacteria in a California hospital; one morning he found a bacteria that could splice DNA, with enzymes (a restriction endonuclease); in March 1973 Boyer and Stanley Norman Cohen worked on an experiment to put a toad gene into a bacteria; the experiment worked, and the bacteria cell produced toad proteins; Paul Berg, of Stanford ...
Rosalind Franklin joined King's College London in January 1951 to work on the crystallography of DNA. By the end of that year, she established two important facts: one is that phosphate groups, which are the molecular backbone for the nucleotide chains, lie on the outside (it was a general consensus at the time that they were at the inside); and the other is that DNA exists in two forms, a ...
The first American newspaper coverage of the discovery of the DNA structure: Saturday, 13 June 1953 The New York Times (PDF) Listen to an oral history interview with Maurice Wilkins Archived 30 January 2012 at the Wayback Machine – a life story interview recorded for National Life Stories at the British Library