Multiple Choice
A mixed infection of two bacteriophage strains is often used for what purpose?
5. Genetics of Bacteria and Viruses
Bacteriophage Genetics
Back5. Genetics of Bacteria and Viruses
Bacteriophage Genetics
- Multiple Choice
A plaque assay studies viruses through what measurement?
- Multiple Choice
A mixed infection of two bacteriophage strains was performed. Infection of bacteriophage strain 1 causes the bacteria to be red and large, while infection of bacteriophage strain 2 causes the bacteria colony to be black and small. The following results were obtained. Using this data, determine the distance between the color and size genes.
- Open QuestionIn 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?
- Open QuestionIn 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?
- Open QuestionWrite a short summary that contrasts how recombination occurs in bacteria and bacteriophages.
- Open Question
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.
- Open Question
What is a prophage, and how is a prophage formed?
- Open Question
Describe the differences between genetic complementation and recombination as they relate to the detection of wild-type lysis by a mutant bacteriophage.
- Open QuestionDefine plaque, lysogeny, and prophage.
- Open QuestionTwo 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
- Open Question
Seven deletion mutations (1 to 7 in the table below) are tested for their ability to form wild-type recombinants with five point mutations (a to e). The symbol "+" indicates that wild-type recombination occurs, and "-" indicates that wild types are not formed. Use the data to construct a genetic map of the order of point mutations, and indicate the segment deleted by each deletion mutation.
- Open QuestionThe bacteriophage genome consists of many genes encoding proteins that make up the head, collar, tail, and tail fibers. When these genes are transcribed following phage infection, how are these proteins synthesized, since the phage genome lacks genes essential to ribosome structure?
- Open QuestionIf a single bacteriophage infects one E. coli cell present on a lawn of bacteria and, upon lysis, yields 200 viable viruses, how many phages will exist in a single plaque if three more lytic cycles occur?
- Open QuestionIf a single bacteriophage infects one E. coli cell present on a lawn of bacteria and, upon lysis, yields 200 viable viruses, how many phages will exist in a single plaque if three more lytic cycles occur?Dilution Factor Assay Results(a) 10⁴ All bacteria lysed(b) 10⁵ 14 plaques(c) 10⁶ 0 plaques