The Double Helix
James Watson & Francis Crick, 1951-1953.
Studies of DNA had revealed much about its chemical and physical nature, but Watson believed that its function could not be understood fully until its structure was known. Crick and Watson used the results from previous studies and X-ray diffraction data from Maurice Wilkins and Rosalind Franklin to help them determine DNA's molecular structure.
By 1953 they had built a model which incorporated all known features of DNA, and proposed the double helix structure which is commonly referred to as the Watson-Crick model of DNA.
The two silver strings symbolize the two phosphate-sugar chains, and the horizonal rods the pairs of bases holding the chains together.
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The Discovery of the Double Helix