Describe what is meant by the term site-specific recombination as used in identifying the processes that lead to the integration of temperate bacteriophages into host bacterial chromosomes during lysogeny or to the formation of specialized transducing phage.

In this chapter, we have focused on genetic systems present in bacteria and on the viruses that use bacteria as hosts (bacteriophages). In particular, we discussed mechanisms by which bacteria and their phages undergo genetic recombination, which allows geneticists to map bacterial and bacteriophage chromosomes. In the process, we found many opportunities to consider how this information was acquired. From the explanations given in the chapter, what answers would you propose to the following questions?How do we know that in bacteriophage T4 the rII locus is subdivided into two regions, or cistrons?

In this chapter, we have focused on genetic systems present in bacteria and on the viruses that use bacteria as hosts (bacteriophages). In particular, we discussed mechanisms by which bacteria and their phages undergo genetic recombination, which allows geneticists to map bacterial and bacteriophage chromosomes. In the process, we found many opportunities to consider how this information was acquired. From the explanations given in the chapter, what answers would you propose to the following questions?How do we know that intergenic exchange occurs in bacteriophages?

Write a short summary that contrasts how recombination occurs in bacteria and bacteriophages.

Define plaque, lysogeny, and prophage.

Two theoretical genetic strains of a virus (a⁻b⁻c⁻ and a⁺b⁺c⁺) were used to simultaneously infect a culture of host bacteria. Of 10,000 plaques scored, the following genotypes were observed. Determine the genetic map of these three genes on the viral chromosome. Decide whether interference was positive or negative.a⁺ b⁺ c⁺ 4100 a⁻ b⁺ c⁻ 160a⁻ b⁻ c⁻ 3990 a⁺ b⁻ c⁺ 140a⁺ b⁻ c⁻ 740 a⁻ b⁻ c⁺ 90a⁻ b⁺ c⁺ 670 a⁺ b⁺ c⁻ 110