BBC - History - Crick and Watson
Watson and Crick describe structure of DNA At Cambridge University, graduate student Francis Crick and research fellow James Watson (b. She suspected that all DNA was helical but did not want to announce this finding until she had. What did the duo actually discover? Many people believe that American biologist James Watson and English physicist Francis Crick discovered DNA in the. James Watson and Francis Crick solved the structure of DNA. When the war ended, Crick continued to work at the Admiralty but he knew he did not want to design In , Francis Crick met James Watson who was visiting Cambridge.
Crick engaged in several X-ray diffraction collaborations such as one with Alexander Rich on the structure of collagen. George Gamow established a group of scientists interested in the role of RNA as an intermediary between DNA as the genetic storage molecule in the nucleus of cells and the synthesis of proteins in the cytoplasm the RNA Tie Club.
It was clear to Crick that there had to be a code by which a short sequence of nucleotides would specify a particular amino acid in a newly synthesized protein. InCrick wrote an informal paper about the genetic coding problem for the small group of scientists in Gamow's RNA group.
Crick proposed that there was a corresponding set of small "adaptor molecules" that would hydrogen bond to short sequences of a nucleic acid, and also link to one of the amino acids. He also explored the many theoretical possibilities by which short nucleic acid sequences might code for the 20 amino acids. Molecular model of a tRNA molecule. During the mid-to-late s Crick was very much intellectually engaged in sorting out the mystery of how proteins are synthesized.
ByCrick's thinking had matured and he could list in an orderly way all of the key features of the protein synthesis process: None of this, however, answered the fundamental theoretical question of the exact nature of the genetic code. In his article, Crick speculated, as had others, that a triplet of nucleotides could code for an amino acid. Some amino acids might have multiple triplet codes.
Crick also explored other codes in which, for various reasons, only some of the triplets were used, "magically" producing just the 20 needed combinations. Crick also used the term " central dogma " to summarize an idea that implies that genetic information flow between macromolecules would be essentially one-way: In his thinking about the biological processes linking DNA genes to proteins, Crick made explicit the distinction between the materials involved, the energy required, and the information flow.
Crick was focused on this third component information and it became the organizing principle of what became known as molecular biology. Crick had by this time become a highly influential theoretical molecular biologist. Proof that the genetic code is a degenerate triplet code finally came from genetics experiments, some of which were performed by Crick. Crick's reaction was to invite Nirenberg to deliver his talk to a larger audience. Discussion of this nomination can be found on the talk page.
November Learn how and when to remove this template message An enduring controversy has been generated by Watson and Crick's use of DNA X-ray diffraction data collected by Franklin and Wilkins. The controversy arose from the fact that some of Franklin's unpublished data were used without her knowledge or consent by Watson and Crick in their construction of the double helix model of DNA. Prior to publication of the double helix structure, Watson and Crick had little direct interaction with Franklin herself.
They were, however, aware of her work, more aware than she herself realized. Watson was present at a lecture, given in Novemberwhere Franklin presented the two forms of the molecule, type A and type B, and discussed the position of the phosphate units on the external part of the molecule.
She also specified the amount of water to be found in the molecule in accordance with other parts of it, data that have considerable importance in terms of the stability of the molecule. She was the first to discover and formulate these facts, which in fact constituted the basis for all later attempts to build a model of the molecule. Before this, both Linus Pauling and Watson and Crick had generated erroneous models with the chains inside and the bases pointing outwards.
It appears that Randall did not communicate effectively with them about Franklin's appointment, contributing to confusion and friction between Wilkins and Franklin. She wrote a series of three draft manuscripts, two of which included a double helical DNA backbone. Her two A form manuscripts reached Acta Crystallographica in Copenhagen on 6 March one day before Crick and Watson had completed their model.
Watson and Crick discover chemical structure of DNA
Franklin's experimental work thus proved crucial in Watson and Crick's discovery. Her experimental results provided estimates of the water content of DNA crystals, and these results were most consistent with the three sugar-phosphate backbones being on the outside of the molecule. Although she at first insisted vehemently that her data did not force one to conclude that DNA has a helical structure, in the drafts she submitted in she argues for a double helical DNA backbone.
Her identification of the space group for DNA crystals revealed to Crick that the DNA strands were antiparallelwhich helped Watson and Crick decide to look for DNA models with two antiparallel polynucleotide strands.
In summary, Watson and Crick had three sources for Franklin's unpublished data: Crick and Watson felt that they had benefited from collaborating with Wilkins. They offered him a co-authorship on the article that first described the double helix structure of DNA. Wilkins turned down the offer, a fact that may have led to the terse character of the acknowledgement of experimental work done at King's College in the eventual published paper.
Rather than make any of the DNA researchers at King's College co-authors on the Watson and Crick double helix article, the solution that was arrived at was to publish two additional papers from King's College along with the helix paper.
Brenda Maddox suggests that because of the importance of her experimental results in Watson and Crick's model building and theoretical analysis, Franklin should have had her name on the original Watson and Crick paper in Nature.
Watson's portrayal of Franklin in The Double Helix written after Franklin's death when libel laws did not apply anymore was negative and gave the appearance that she was Wilkins' assistant and was unable to interpret her own DNA data. While Franklin's experimental work proved important to Crick and Watson's development of a correct model, she herself could not realize it at the time.
A Science Odyssey: People and Discoveries: Watson and Crick describe structure of DNA
Bernal's Lab at Birkbeck College with the tobacco mosaic virus extending ideas on helical construction. One colleague from the Salk Institute described him as "a brainstorming intellectual powerhouse with a mischievous smile Francis was never mean-spirited, just incisive.
He detected microscopic flaws in logic. In a room full of smart scientists, Francis continually reearned his position as the heavyweight champ. For example, Crick advocated a form of positive eugenics in which wealthy parents would be encouraged to have more children.
Francis Crick :: DNA from the Beginning
It is not a subject at the moment which we can tackle easily because people have so many religious beliefs and until we have a more uniform view of ourselves I think it would be risky to try and do anything in the way of eugenics AguillardCrick joined a group of other Nobel laureates who advised, "'Creation-science' simply has no place in the public-school science classroom. The human dilemma is hardly new.
We find ourselves through no wish of our own on this slowly revolving planet in an obscure corner of a vast universe. Our questioning intelligence will not let us live in cow-like content with our lot. We have a deep need to know why we are here. What is the world made of? More important, what are we made of? In the past religion answered these questions, often in considerable detail.
Now we know that almost all these answers are highly likely to be nonsense, having sprung from man's ignorance and his enormous capacity for self-deception The simple fables of the religions of the world have come to seem like tales told to children. Even understood symbolically they are often perverse, if not rather unpleasant Humanists, then, live in a mysterious, exciting and intellectually expanding world, which, once glimpsed, makes the old worlds of the religions seem fake-cosy and stale I do not respect Christian beliefs.
I think they are ridiculous. If we could get rid of them we could more easily get down to the serious problem of trying to find out what the world is all about. At what moment does a baby get a soul? Crick stated his view that the idea of a non-material soul that could enter a body and then persist after death is just that, an imagined idea. For Crick, the mind is a product of physical brain activity and the brain had evolved by natural means over millions of years.
He felt that it was important that evolution by natural selection be taught in schools and that it was regrettable that English schools had compulsory religious instruction. He also considered that a new scientific world view was rapidly being established, and predicted that once the detailed workings of the brain were eventually revealed, erroneous Christian concepts about the nature of humans and the world would no longer be tenable; traditional conceptions of the "soul" would be replaced by a new understanding of the physical basis of mind.
He was sceptical of organized religionreferring to himself as a sceptic and an agnostic with "a strong inclination towards atheism". Some time later a large donation was made to establish a chapel and the College Council decided to accept it.
Crick resigned his fellowship in protest. His speculations were later published in Nature. He also discussed what he described as a possible new direction for research, what he called "biochemical theology".
Crick wrote "so many people pray that one finds it hard to believe that they do not get some satisfaction from it". He speculated that there might be a detectable change in the level of some neurotransmitter or neurohormone when people pray.
He might have been imagining substances such as dopamine that are released by the brain under certain conditions and produce rewarding sensations.
Crick's suggestion that there might someday be a new science of "biochemical theology" seems to have been realized under an alternative name: Crick asked in "and if some of the Bible is manifestly wrong, why should any of the rest of it be accepted automatically? And what would be more important than to find our true place in the universe by removing one by one these unfortunate vestiges of earlier beliefs?
InCrick took the place of Leslie Orgel at a meeting where Orgel was to talk about the origin of life. Crick speculated about possible stages by which an initially simple code with a few amino acid types might have evolved into the more complex code used by existing organisms. InWatson attended a lecture by Franklin on her work to date. She had found that DNA can exist in two forms, depending on the relative humidity in the surrounding air.
This had helped her deduce that the phosphate part of the molecule was on the outside. Watson returned to Cambridge with a rather muddy recollection of the facts Franklin had presented, though clearly critical of her lecture style and personal appearance.
Based on this information, Watson and Crick made a failed model. It caused the head of their unit to tell them to stop DNA research. But the subject just kept coming up.
Franklin, working mostly alone, found that her x-ray diffractions showed that the "wet" form of DNA in the higher humidity had all the characteristics of a helix. She suspected that all DNA was helical but did not want to announce this finding until she had sufficient evidence on the other form as well.
In January,he showed Franklin's results to Watson, apparently without her knowledge or consent. Crick later admitted, "I'm afraid we always used to adopt -- let's say, a patronizing attitude towards her.
- Crick and Watson (1916-2004)
Crick had just learned of Chargaff's findings about base pairs in the summer of He added that to the model, so that matching base pairs interlocked in the middle of the double helix to keep the distance between the chains constant.
Watson and Crick showed that each strand of the DNA molecule was a template for the other. During cell division the two strands separate and on each strand a new "other half" is built, just like the one before.