• Not a single scientist but two Watson and Crick in 1953. Here is a link to know a more detailed: Watson & Crick: Hope, this will give you the whole answer and you mignt read the article in the following link too. DNA structure:
  • "Atom and bond models may be further classified along a spectrum between an emphasis on atom representation to an emphasis on bond representation. Space-filling models represent the atoms as spheres whose radii are proportional to the atom's van der Waals radius. The best known of this type of model is the Corey-Pauling-Koltun model. The original models of Corey and Pauling (1953) were made of hard wood (1 inch per angstrom) and plastic (0.5 inch per angstrom). The wood models were connected with steel rods and clamps, the plastic models with snap fasteners." Source and further information: "In 1951, based on the structures of amino acids and peptides and the planarity of the peptide bond, Pauling and colleagues correctly proposed the alpha helix and beta sheet as the primary structural motifs in protein secondary structure. This work exemplified his ability to think unconventionally; central to the structure was the unorthodox assumption that one turn of the helix may well contain a non-integral number of amino acid residues. Pauling then proposed that deoxyribonucleic acid (DNA) was a triple helix;[46] however, his model contained several basic mistakes, including a proposal of neutral phosphate groups, an idea that conflicted with the acidity of DNA. Sir Lawrence Bragg had been disappointed that Pauling had won the race to find the alpha helix structure of proteins. Bragg's team had made a fundamental error in making their models of protein by not recognizing the planar nature of the peptide bond. When it was learned at the Cavendish Laboratory that Pauling was working on molecular models of the structure of DNA, Watson and Crick were allowed to make a molecular model of DNA using unpublished data from Maurice Wilkins and Rosalind Franklin at King's College. Early in 1953 James D. Watson and Francis Crick proposed a correct structure for the DNA double helix. One of the impediments facing Pauling in this work was that he did not have access to the high quality X-ray diffraction photographs of DNA taken by Rosalind Franklin, which Watson and Crick had seen. He planned to attend a conference in England, where he might have been shown the photos, but he could not do so because his passport was withheld in 1952 by the State Department, on suspicions that he had Communist sympathies. This was at the start of the McCarthy period in the United States." Source and further information: The wrong Pauling model was made of metal and wood, the Watson and Crick model was of metal. Linus Pauling's DNA model: Watson and Crick model: Article "A Structure for Deoxyribose Nucleic Acid":

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