On this day 1953 Francis Crick, James Watson & Rosalind Franklin’s discovery of the double helix structure of DNA is published in “Nature” magazine.
American biologist James Watson and British physicist Francis Crick came up with their famous model of the DNA double helix. They were the first to cross the finish line in this scientific “race,” with others such as Linus Pauling (who discovered protein secondary structure) also trying to find the correct model. Rather than carrying out new experiments in the lab, Watson and Crick mostly collected and analyzed existing pieces of data, putting them together in new and insightful ways.
Some of their most crucial clues to DNA’s structure came from Rosalind Franklin, a chemist working in the lab of physicist Maurice Wilkins. Franklin was an expert in a powerful technique for determining the structure of molecules, known as X-ray crystallography. When the crystallized form of a molecule such as DNA is exposed to X-rays, some of the rays are deflected by the atoms in the crystal, forming a diffraction pattern that gives clues about the molecule’s structure.
Franklin’s crystallography gave Watson and Crick important clues to the structure of DNA. Some of these came from the famous “image 51,” a remarkably clear and striking X-ray diffraction image of DNA produced by Franklin and her graduate student. (A modern example of the diffraction pattern produced by DNA is shown above.) To Watson, the X-shaped diffraction pattern of Franklin’s image immediately suggested a helical, two-stranded structure for DNA.
In 1962, James Watson, Francis Crick, and Maurice Wilkins were awarded the Nobel Prize in Medicine. Unfortunately, by then Franklin had died, and Nobel prizes are not awarded posthumously.