Genetics: Analysis and Principles 5th Edition by Robert Brooker

Exercise 34

In the experimental strategy described in Figure 7.18, explain why it was necessary to dilute the phage preparation used to infect E. coli B so much more than the phage preparation used to infect E. coli K12( ).FIGURE 7.18 Benzer'smethod of intragenic mapping in the rll region. The coinfection carried out at the top of this figure was done using a great excess of phages, making it likely that the E. coli B cells will be coinfected with both strains. However, the infection experiment toward the bottom of the figure was done at a lower phage concentration such that an E. coli B cell or E. coli K12( ) cell would be infected with a single phage.