Photo 51 is an X-ray based fiber diffraction image of a paracrystalline gel composed of DNA fiber [1] taken by Raymond Gosling, [2] [3] a postgraduate student working under the supervision of Rosalind Franklin in May 1952 at King's College London, while working in Sir John Randall's group. [4] [5] [6] [7] [8] The image was tagged "photo 51" because it was the 51st diffraction photograph that Franklin had taken. [9] It was critical evidence [10] in identifying the structure of DNA. [11]
According to Raymond Gosling's later account, although photo 51 was an exceptionally clear diffraction pattern of the "B" form of DNA, Franklin was more interested in solving the diffraction pattern of the "A" form of DNA, so she put Gosling's photo 51 to the side. When it had been decided that Franklin would leave King's College, Gosling showed the photograph to Maurice Wilkins [12] [13] (who would become Gosling's advisor after Franklin left).
A few days later, Wilkins showed the photo to James Watson after Gosling had returned to working under Wilkins' supervision. Franklin did not know this at the time because she was leaving King's College London. Randall, the head of the group, had asked Gosling to share all his data with Wilkins. [5] Watson recognized the pattern as a helix because his co-worker Francis Crick had previously published a paper of what the diffraction pattern of a helix would be. [12] Watson and Crick used characteristics and features of Photo 51, together with evidence from multiple other sources, to develop the chemical model of the DNA molecule. Their model, along with papers by Wilkins and colleagues, and by Gosling and Franklin, were first published, together, in 1953, in the same issue of Nature.
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 four years earlier, and although there was not yet a rule against posthumous awards, [14] the Nobel Committee generally does not make posthumous nominations. [15] Gosling's work also was not cited by the prize committee.
The photograph provided key information that was essential for developing a model of DNA. [11] [16] The diffraction pattern determined the helical nature of the double helix strands (antiparallel). The outside of the DNA chain has a backbone of alternating deoxyribose and phosphate moieties, and the base pairs, the order of which provides codes for protein building and thereby inheritance, are inside the helix. Watson and Crick's calculations from Gosling and Franklin's photography gave crucial parameters for the size and structure of the helix. [16]
Photo 51 became a crucial data source [17] that led to the development of the DNA model and confirmed the prior postulated double helical structure of DNA, which were presented in the series of three articles in the journal Nature in 1953.
As historians of science have re-examined the period during which this image was obtained, considerable controversy has arisen over both the significance of the contribution of this image to the work of Watson and Crick, as well as the methods by which they obtained the image. Franklin had been hired independently of Maurice Wilkins, who, taking over as Gosling's new supervisor, showed Photo 51 to Watson and Crick without Franklin's knowledge. Whether Franklin would have deduced the structure of DNA on her own, from her own data, had Watson and Crick not obtained Gosling's image, is a hotly debated topic, [11] [16] [18] [19] made more controversial by the negative caricature of Franklin presented in the early chapters of Watson's history of the research on DNA structure, The Double Helix . [16] [20] [21] Watson admitted his distortion of Franklin in his book, noting in the epilogue: "Since my initial impressions about [Franklin], both scientific and personal (as recorded in the early pages of this book) were often wrong, I want to say something here about her achievements." [22]
Deoxyribonucleic acid is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.
Francis Harry Compton Crick 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.
James Dewey Watson is an American molecular biologist, geneticist, and zoologist. In 1953, he co-authored with Francis Crick the academic paper proposing the double helix structure of the DNA molecule. Watson, Crick and Maurice Wilkins were awarded the 1962 Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material".
Rosalind Elsie Franklin was a British chemist and X-ray crystallographer whose work was central to the understanding of the molecular structures of DNA, RNA, viruses, coal, and graphite. Although her works on coal and viruses were appreciated in her lifetime, Franklin's contributions to the discovery of the structure of DNA were largely unrecognized during her life, for which Franklin has been variously referred to as the "wronged heroine", the "dark lady of DNA", the "forgotten heroine", a "feminist icon", and the "Sylvia Plath of molecular biology".
Maurice Hugh Frederick Wilkins was a New Zealand-born British biophysicist and Nobel laureate whose research spanned multiple areas of physics and biophysics, contributing to the scientific understanding of phosphorescence, isotope separation, optical microscopy and X-ray diffraction. He is known for his work at King's College London on the structure of DNA.
The Double Helix: A Personal Account of the Discovery of the Structure of DNA is an autobiographical account of the discovery of the double helix structure of DNA written by James D. Watson and published in 1968. It has earned both critical and public praise, along with continuing controversy about credit for the Nobel award and attitudes towards female scientists at the time of the discovery.
In molecular biology, the term double helix refers to the structure formed by double-stranded molecules of nucleic acids such as DNA. The double helical structure of a nucleic acid complex arises as a consequence of its secondary structure, and is a fundamental component in determining its tertiary structure. The structure was discovered by Rosalind Franklin and her student Raymond Gosling, but the term "double helix" entered popular culture with the publication in 1968 of The Double Helix: A Personal Account of the Discovery of the Structure of DNA by James Watson.
Raymond George Gosling was a British scientist. While a PhD student at King's College, London he worked under the supervision of Maurice Wilkins and Rosalind Franklin. The crystallographic experiments of Franklin and Gosling, together with others by Wilkins, produced data that helped James Watson and Francis Crick to infer the structure of DNA.
"Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid" was the first article published to describe the discovery of the double helix structure of DNA, using X-ray diffraction and the mathematics of a helix transform. It was published by Francis Crick and James D. Watson in the scientific journal Nature on pages 737–738 of its 171st volume.
Herbert Rees Wilson FRSE was a physicist, who was one of the team who worked on the structure of DNA at King's College London, under the direction of Sir John Randall.
Alexander Rawson Stokes was a British physicist at Royal Holloway College, London and later at King's College London. He was most recognised as a co-author of the second of the three papers published sequentially in Nature on 25 April 1953 describing the correct molecular structure of DNA. The first was authored by Francis Crick and James Watson, and the third by Rosalind Franklin and Raymond Gosling.
William Thomas Astbury FRS was an English physicist and molecular biologist who made pioneering X-ray diffraction studies of biological molecules. His work on keratin provided the foundation for Linus Pauling's discovery of the alpha helix. He also studied the structure for DNA in 1937 and made the first step in the elucidation of its structure.
The history of molecular biology begins in the 1930s with the convergence of various, previously distinct biological and physical disciplines: biochemistry, genetics, microbiology, virology and physics. With the hope of understanding life at its most fundamental level, numerous physicists and chemists also took an interest in what would become molecular biology.
Molecular models of DNA structures are representations of the molecular geometry and topology of deoxyribonucleic acid (DNA) molecules using one of several means, with the aim of simplifying and presenting the essential, physical and chemical, properties of DNA molecular structures either in vivo or in vitro. These representations include closely packed spheres made of plastic, metal wires for skeletal models, graphic computations and animations by computers, artistic rendering. Computer molecular models also allow animations and molecular dynamics simulations that are very important for understanding how DNA functions in vivo.
Sir John Turton Randall, was an English physicist and biophysicist, credited with radical improvement of the cavity magnetron, an essential component of centimetric wavelength radar, which was one of the keys to the Allied victory in the Second World War. It is also the key component of microwave ovens.
In addition to the variety of verified DNA structures, there have been a range of proposed DNA models that have either been disproven, or lack evidence.
Anne Sayre was an American writer well known for her biography of Rosalind Franklin, one of the discoverers of the structure of DNA.
Photograph 51 is a play by Anna Ziegler. Photograph 51 opened in the West End of London in September 2015. The play focuses on the often-overlooked role of X-ray crystallographer Rosalind Franklin in the discovery of the double helix structure of DNA while working at King's College London. This play won the third STAGE International Script Competition in 2008. The title comes from Photo 51, the nickname given to an X-ray diffraction image taken by Raymond Gosling in May, 1952, under the supervision of Rosalind Franklin. The one-act play runs for 95 minutes with no intermission.
Rosalind Franklin and DNA is a biography of an English chemist Rosalind Franklin (1920–1958) written by her American friend Anne Sayre in 1975. 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. DNA itself had become "life's most famous molecule". While working at the King's College London in 1951, she discovered two types of DNA called A-DNA and B-DNA. Her X-ray images of DNA indicated helical structure. Her X-ray image of B-DNA taken in 1952 became the best evidence for the structure of DNA. For the discovery of the correct chemical structure of DNA, the Nobel Prize in Physiology or Medicine 1962 was shared by her colleagues and close researchers James Watson, Francis Crick and Maurice Wilkins; she had died four years earlier in 1958 making her ineligible for the award.
Florence Ogilvy Bell, later Florence Sawyer, was a British scientist who contributed to the discovery of the structure of DNA. She was an X-ray crystallographer in the lab of William Astbury. In 1938 they published a paper in Nature that described the structure of DNA as a "Pile of Pennies".
PHOTO 51 rosalind franklin.
Raymond Gosling: 'I took it down the corridor and gave it to him because it had reached the stage now when Rosalind was going to leave, so she suggested that I go down the corridor and give this beautiful structure B pattern, this photo 51, to Maurice. Maurice couldn't believe it when I offered it to him. He couldn't believe that I hadn't stolen it from her desk. He didn't think that she could ever offer him something as interesting as this.'
On January 30, 1953, Watson visited King's. Without Franklin's permission, Wilkins showed her data to Watson—in particular, an X-ray crystallograph (of May 1952) that provided unquestionable evidence of the helical structure of DNA.
DNA structure research at King's College London 1947–1959 | ||
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