chapter  2
21 Pages

Seymour Benzer and the convergence of molecular biology with classical genetics

WithFrederic L. Holmes

Between 1954 and 1961 Seymour Benzer mapped the fine structure of the rII region of the genome of the bacteriophage T4. This work achieved a historical significance far beyond the small bit of genetic material on which it was carried out. In the early years of the “double helix,” Benzer’s evidence that the genetic map is linear down to dimensions approaching those of nucleotides provided powerful and timely support for the hypothesis that information embedded in the order of the DNA base pairs codes for the order of amino acids in proteins. His evidence that the units of recombination, mutation, and function associated with the gene had different dimensions led him to propose three new terms to replace the “classical gene” with more rigorously defined concepts. Yet the broader similarity between his fine structure maps and those that had earlier been constructed for the location of genes on the chromosomes of organisms such as the fruit fly was striking enough so that Benzer has been seen as the person who, more than anyone else, provided the “bridge” that enabled classical genetics to “adapt to the molecular age.”