Crick, Francis (1916–2004)

Francis Harry Compton Crick was not only codiscoverer of the DNA double helix, but also [Page 193]maintained a long career as a science communicator. Born near Northampton, England, the son of a shoe manufacturer, Crick began a PhD in physics before World War II at University College, London. During the war, he worked for the Royal Navy on the design and the detection of mines. Like many physicists after the war, he decided to move to biology and applied for funding in 1947. He began cell biophysics in Cambridge, England, and in 1949, he opted for protein crystallography, rejoining Max Perutz's unit for the study of the structure of biological systems at the Cavendish Laboratory, directed by Lawrence Bragg. There, he worked toward a PhD on protein structure but, with James D. Watson, discovered the structure of the double helix of DNA before graduating in July 1953.

In Cambridge, Crick also participated in the creation of the first Laboratory of Molecular Biology (LMB) in Europe. Later the same year, he received the Nobel Prize of Medicine together with James D. Watson and Maurice H. F. Wilkins for their work on DNA. In the LMB, Crick worked on the genetic code and then chromosome structure. In 1977, he left the field of molecular biology to pursue research in neuroscience. In this field, he focused on consciousness and worked at the Salk Institute in San Diego, California.

As a molecular biologist, Crick was the discipline's best-known theoretician. He did perform experiments, but as Matt Ridley has aptly noted in his biography, Crick's greatest skill was conjecturing. Throughout his career, he wrote numerous papers reporting hypotheses and models. The double helix paper was one of them. His prominent ability was to synthesize a great number of facts in a theoretical model. He was also good at explaining new theory in a clear and captivating way. In the 1960s, the then nascent field of molecular biology was indeed characterized by new jargon about the cell.

While biochemists saw the cell as a factory that produces proteins, molecular biologists saw the cell as an information machine that deals with information flux, from DNA to proteins. Both metaphors were powerful, but the latter was fashionable in the postwar era when computers started to disseminate. From the molecular biology point of view, DNA stores genetic information into the sequence of its four bases (A, C, G, and T). The DNA sequence is translated into a protein sequence written in a 20-letter alphabet. The genetic code and a complex biochemical apparatus are needed to realize this translation. Crick made a contribution at every step of this scheme, which was uncovered between 1950 and 1965. He provided the main theoretical framework of information transfers in molecular biology, the so-called central dogma.

After uncovering the double helix structure, which suggests how genetic information is stored and copied, he attempted to theoretically decipher the genetic code, but failed. He nevertheless made invaluable contributions both theoretically (involving the adaptor and the wobble hypothesis) and at the bench (showing with Sydney Brenner that the code is made of triplets of bases). The adaptor hypothesis stated that proteins are not directly molded on DNA but that an adaptor molecule exists between the two. This molecule was discovered soon after and was called transfer RNA. The wobble hypothesis explained how different triplets of bases have the same meaning in the protein's alphabet.

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