The Process of Discovering DNA and Incorrect Structures of DNA
The famous double helical structure of DNA was discovered by Francis Crick and James Watson in 1953 (Watson, 1968), and while their discovery of the model is famous many other structures were proposed before the double helix structure. There were many other people also searching for the structure of DNA at the same time as Watson and Crick, who also published papers showing models of DNA that were eventually discarded. This essay will look at three of these initially proposed structures. The three structures that will be explored are the Mg++ Ion Structure developed by Watson and Crick, the Pauling-Corey Structure developed by Pauling and Corey and the Fraser Structure developed …show more content…
Fraser’s structure wasn’t far off the true structure of DNA but there were still some mistakes in his proposed model. The Fraser structure consisted of a three-chained helix with the sugar-phosphate chains on the outside and the bases on the inside of the model (Fraser, 1953). The model was held together by van der Waals between the bases as well as hydrogen bonds that form between all three of the strands. The bases in this model are also slightly tilted and the hydrogen bonds form a spiral around the helix (Fraser, …show more content…
Fraser had been told separately by both Franklin and Wilkins that DNA had to contain three chains, and as such Fraser’s model contained three chains. However, the positioning of the three strands to equally fill space contradicted data that the X-ray pictures showed (Dna and social responsibility, 2010). The actual hydrogen bonding between the three chains that helped keep the structure together was also wrong as well as the structure not following Chargaff’s rules about having equal amounts of A and T, and G and C further proving the structure incorrect (Dna and social responsibility,
The famous double helical structure of DNA was discovered by Francis Crick and James Watson in 1953 (Watson, 1968), and while their discovery of the model is famous many other structures were proposed before the double helix structure. There were many other people also searching for the structure of DNA at the same time as Watson and Crick, who also published papers showing models of DNA that were eventually discarded. This essay will look at three of these initially proposed structures. The three structures that will be explored are the Mg++ Ion Structure developed by Watson and Crick, the Pauling-Corey Structure developed by Pauling and Corey and the Fraser Structure developed …show more content…
Fraser’s structure wasn’t far off the true structure of DNA but there were still some mistakes in his proposed model. The Fraser structure consisted of a three-chained helix with the sugar-phosphate chains on the outside and the bases on the inside of the model (Fraser, 1953). The model was held together by van der Waals between the bases as well as hydrogen bonds that form between all three of the strands. The bases in this model are also slightly tilted and the hydrogen bonds form a spiral around the helix (Fraser, …show more content…
Fraser had been told separately by both Franklin and Wilkins that DNA had to contain three chains, and as such Fraser’s model contained three chains. However, the positioning of the three strands to equally fill space contradicted data that the X-ray pictures showed (Dna and social responsibility, 2010). The actual hydrogen bonding between the three chains that helped keep the structure together was also wrong as well as the structure not following Chargaff’s rules about having equal amounts of A and T, and G and C further proving the structure incorrect (Dna and social responsibility,