Unformatted text preview: Science and Technology in the History 3c, Fall 2007 20th Century Iconic image of an iconic event Week 8: The postwar transformation of biology Lecture 15: The double helix in perspective James Watson and Francis Crick with their double helical model of DNA Photograph by Antony Barrington Brown (1953) Outline 1. The double helix in context 2. The reception of Watson and Crick’s Crick’ work in the 1950s 3. The debate on the origins of molecular biology and the publication of Watson’s book Watson’ 4. The double helix as cultural icon 5. Beyond the double helix Nature 422, 24 April 2003, p. 835 1. The double helix in context Watson and Crick propose a double helical model of DNA Nature 25 April 1953 Nature The double helix as cultural icon and fetish object 1 Novel features of the structure of DNA:
Rosalind Franklin’s XFranklin’ Xray photograph of DNA (B form) Nature 25 April 1953 double helical conformation pairing of complementary bases (copying mechanism, mechanism for mutation) Known features: 1. DNA recognized as the genetic material (Avery experiments in 1944, Hershey and Chase experiments 1952) 2. Chemical structure of DNA 3. Chargaff’s work on base ratios The complementary structure of DNA The
‘It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetical material’ (Watson and Crick, Nature 25 April 1953) material’ 4. Notion of a genetic code and the language of information pre-dated Watson and Crick’s work Phage infection: only DNA enters the bacterial cell. Known features: 1. DNA recognized as the genetic material (Avery experiments in 1944, Hershey and Chase experiments 1952) 2. Chemical structure of DNA 3. Chargaff’s work on base ratios 4. Notion of a genetic code and the language of information pre-dated Watson and Crick’s work Drawing by 5-year old Martha Jane 2 Biological importance of DNA well proven Hope that 3D structure would reveal working mechanism for DNA and its double function: replication and protein synthesis ‘unwinding’ problem coding problem DNA replication according to the scheme of Watson and Crick: The ‘unwinding problem’. problem’ Protein synthesis Cartoon by George Gamow Diamond code proposed by George Gamow (1954) The genetic code
2. Reception in the 1950s
‘Quiet debut’ for the double helix 3 ... it appeared to take a long time before the excitement sank in at the Cavendish. There was much more excitement at the Cavendish at that time over the mathematics of the Slinky wire frame. You know the slinky, the little wire frame that walks down the stairs? This came out at that time and one of the scientists brought one back from the States and I remember seeing all the scientific staff come from the tea room and watch this walk down the stairs and then intense discussions on the mathematics of how it was working. That seemed to excite them a lot more than the DNA model actually itself (Michael Fuller, interview 1998). I don't know what people thought of us at the time, because remember, it was not that the structure of the helix made a big difference. Everybody was quite pleased. But it was not regarded as sort of, you know ... the way it is nowadays, as an overwhelming breakthrough (Francis Crick, interview 1993). The elucidation of the double-helical structure of DNA in 1953 created almost no stir outside the small band of scientists who were waiting for the discovery to be made (Watson and Tooze, The DNA Story, 1981, p. vii) News Chronicle 15 May 1953 15
The first media report on the double helix Photographs of Watson, Crick and the double helix by Antony Barrington Brown (1953) Contact prints by Antony Barrington Brown (1953) Replica of Watson and Crick’s DNA model in the Science Museum in London 4 Papers published in Nature referring to DNA and to the double helix 1950-1960. From R. Olby, Nature 1950Olby, Nature 23 January 2003, p. 403. An original DNA base from Watson and Crick’s model signed by Francis Crick As you know, much beautiful experimental work has been done by biochemists in recent years, all of which has confirmed the rightness of Watson and Crick's conclusions. But so that the contribution of these younger scientists should not be forgotten, I feel we should acknowledge it and refer to it as the Crick-Watson Crickmodel of D.N.A., because it was quite novel and unexpected when they first put it forward (W. Lawrence Bragg, November 1959). 3. The debate on the origins of molecular biology and the publication of Watson’s book Watson’
What provoked change in attitude? Nobel Prize 1962 (no indication that protein work less prominent) Debate on the ‘origins’ of molecular biology The Double Helix by Watson (1968) First edition (cover) Festschrift for Max Delbrueck 1966 (titel page) Review by John Kendrew in Scientific American 5 The book that could not go to Harvard mixed reaction by scientists (see Chargaff review) enthusiastic reception by broader public treatment of Rosalind Franklin (more next time) Book established basic narrative of the discovery including its scandals 4. The double helix as cultural icon launch of the human genome project gives double helix new prominence (‘Race to the double helix’ dates from this period) The symbolic and aesthetic value of the double helix Galacidalacidesoxyribonucleicacid by Salvador Dali (1963) … the virtual, superdelicate, extravagant and hyperaesthetic images of the living molecular structures of the future, that is the double spiral of Crick and Watson, Jacob’s ladder of genetic angels, the only structure linking man to God (Dali, 1970) Model of myoglobin, the first protein whose structure was determined Model myoglobin, Summary Double helix has acquired its iconic value only retrospectively (it is wrong to project this importance back in time) Watson’s popular account together with the image of the double helix played decisive role To understand postwar importance of genetics we have to look beyond double helix Robin and Batman looking at the DNA model 6 ...
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