167 5.4 Bacteriophage genetics animal and plant viruses. In this way bacterial viruses have provided an important model system. These viruses, which parasitize and kill bacteria, can be used in two different types of genetic analysis. First, two distinct phage genotypes can be crossed to measure recombination and hence map the viral genome. Second, bacteriophages can be used as a way of bringing bacterial genes together for linkage and other genetic studies. We will study this in the next section. In addition, as we shall see in Chapter 11, phages are used in DNA tech-nology as carriers, or vectors, of foreign DNA inserts from any organism. Before we can understand phage genetics, we must ﬁrst examine the infection cycle of phages. Infection of bacteria by phages Most bacteria are susceptible to attack by bacterio-phages. A phage consists of a nucleic acid “chromosome” (DNA or RNA) surrounded by a coat of protein mole-cules. Phage types are identiﬁed not by species names but by symbols, for example, phage T4, phage
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.