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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.
Franklin was a physical chemist who made pivotal research in the discovery of the structure of DNA, known as "the most important discovery" in biology. [1] [2] DNA itself had become "life's most famous molecule". [3] While working at the King's College London in 1951, she discovered two types of DNA called A-DNA and B-DNA.
DNA can be twisted like a rope in a process called DNA supercoiling. With DNA in its "relaxed" state, a strand usually circles the axis of the double helix once every 10.4 base pairs, but if the DNA is twisted the strands become more tightly or more loosely wound. [43]
Using these x-rays and information already known about the chemistry of DNA, James D. Watson and Francis Crick demonstrated the molecular structure of DNA in 1953. [ 22 ] [ 23 ] Together, these discoveries established the central dogma of molecular biology , which states that proteins are translated from RNA which is transcribed by DNA.
This is an accepted version of this page This is the latest accepted revision, reviewed on 12 December 2024. British X-ray crystallographer (1920–1958) This article is about the chemist. For the Mars rover named after her, see Rosalind Franklin (rover). Rosalind Franklin Franklin with a microscope in 1955 Born Rosalind Elsie Franklin (1920-07-25) 25 July 1920 Notting Hill, London, England ...
Two categories of macromolecules in particular are the focus of the molecular biologist: 1) nucleic acids, among which the most famous is deoxyribonucleic acid (or DNA), the constituent of genes, and 2) proteins, which are the active agents of living organisms. One definition of the scope of molecular biology therefore is to characterize the ...
Francis Harry Compton Crick OM FRS [3] [4] (8 June 1916 – 28 July 2004) was an English molecular biologist, biophysicist, and neuroscientist.He, James Watson, Rosalind Franklin, and Maurice Wilkins played crucial roles in deciphering the helical structure of the DNA molecule.
As duplex DNA became the predominant form of the genetic material, the mechanism of genetic recovery evolved into the more complex process of meiotic recombination, found today in most species. It thus appears likely that sexual reproduction arose early in the evolution of cells and has had a continuous evolutionary history.