III.

Identifying the Structure of DNA

In 1949 Crick moved to the Cavendish Laboratory at Cambridge University to pursue his doctoral degree. Working under British physicist and Nobel laureate Sir William Lawrence Bragg, Crick studied the structure of proteins using X-ray diffraction. X-ray diffraction provides X-ray patterns of a molecule’s chemical structure. He eventually moved to a unit of the Medical Research Council (MRC), a publicly funded laboratory located at Cambridge University. At MRC, Crick found himself in talented company. He worked under the guidance of Austrian-born British biochemist Max Perutz and alongside British chemist John Kendrew, two future Nobel laureates. Crick initially studied the structure of hemoglobin, a red, iron-rich protein that carries oxygen in the blood. It was not long, however, before Crick became more interested in studying the structure of DNA.

In 1951 Watson joined Crick’s laboratory at MRC. Crick and Watson shared the same passionate desire to determine the structure of DNA and, over the next two years, they worked together on the problem. American biochemist Linus Pauling had earlier shown success in building scale models to identify the structure of proteins. Crick and Watson decided to use that approach to study DNA. At the time, Wilkins and British chemist Rosalind Franklin at King’s College, London, were using X-ray diffraction analysis to study the DNA molecule. Crick and Watson applied the diffraction studies created by Wilkins and Franklin to their own research.

After a few missteps, Crick and Watson used the X-ray diffraction patterns created by Franklin to develop a three-dimensional model for the structure of DNA. This model depicted DNA as two complementary strands twisted into a double helix.

In 1953 Crick and Watson published their findings in the science journal Nature. Because of their work, scientists were able to understand and describe living things for the first time in terms of the structure and interaction of molecules. Recognized as one of the most significant discoveries of the 20th century, the identification of the structure of DNA affects practically every scientific discipline in the life sciences.