Introduction to Genetic Analysis 159

Introduction to Genetic Analysis 159 - 158 Chapter 5 The...

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Unformatted text preview: 158 Chapter 5 The Genetics of Bacteria and Their Viruses LINEAR TRANSMISSION OF THE HFR GENES FROM A FIXED POINT A clearer view of the behavior of Hfr strains was obtained in 1957, when Elie Wollman and Franois Jacob investigated the pattern of transmission of Hfr genes to F cells during a cross. They crossed Hfr azi r ton r lac gal str s F azi s ton s lac gal str r At specific times after mixing, they removed samples, which were each put in a kitchen blender for a few seconds to separate the mating cell pairs. This procedure is called interrupted mating. The sample was then plated onto a medium containing streptomycin to kill the Hfr donor cells, which bore the sensitivity allele str s .The surviving str r cells then were tested for the presence of alleles from the donor genome. Any str r cell bearing a donor allele must have taken part in conjugation; such cells are called excon- jugants. Figure 5-11a shows a plot of the results, showing a time course of entry of each donor allele...
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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.

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