Читать книгу Snyder and Champness Molecular Genetics of Bacteria - Tina M. Henkin - Страница 39

At the same time, experiments with bacteria and phages were also contributing to the view that genes were linear arrays of nucleotides in the DNA. By the early 1950s, recombination had been well demonstrated in higher organisms, including fruit flies. However, recombination was thought to occur only between mutations in different genes and not between mutations in the same gene. This led to the idea that genes were like “beads on a string” and that recombination is possible between the “beads,” or genes, but not within a gene. In 1955, Seymour Benzer disproved this hypothesis by using the power of phage genetics to show that recombination is possible within the rII genes of phage T4. He mapped numerous mutations in the rII genes, thereby demonstrating that genes are linear arrays of mutable sites in the DNA. Later experiments with other phage and bacterial genes showed that the sequence of nucleotides in the DNA directly determines the sequence of amino acids in the protein product of the gene.