Review Questions for lecture 15

Review Questions for lecture 15 - Review Questions for...

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Review Questions for lecture 15 Be comfortable with the following terms restriction/modification system methylase restriction endonuclease CRISPR Altruistic suicide Predator Prey Transduction Conjugation Transformation Gene Transfer Agent (“GTA”) Lateral Gene Tranfer Horizontal Gene Transfer Homologous Recombination RecA Wild-type Mutation Duplication Complementation Selection If λ is growing lysogenically in E. coli , what gene(s) must be expressed if the phage is to escape and grow lytically? In the short term, what would happen if the promoter for the cro gene were deleted or if there were a nonsense mutation in the gene for cro—could the λ ever escape the cell? In the long term, what would happen to 48,500 base pairs of DNA that wasn’t being transcribed and didn’t contribute to the fitness of the cell? What sort of mutation in an addiction module would inactivate the module? If the addiction module experienced such a mutation, what would happen to it over evolutionary time, and why? What sort of mutation in an addiction module would kill the cell, and why? Is one sort of mutation more likely than the other? How do viruses control bacterial populations? Can viruses spread more rapidly in dense populations or in diffuse populations? Can the lessons learned about bacterial viruses inform our understanding of the viruses that affect humans? How does the restriction-modification system protect a cell against all foreign DNA? Does it help to defend the cell against Q β ? Explain how the CRISPR system is a specific defense, while the restriction-modification is a general defense against viruses. How does CRISPR “remember”? Can this memory be inherited? Some researchers have used CRISPR sequences to understand the history of a cell—what viruses it has been exposed to over the generations. How is this possible? How can a virus avoid the CRISPR defense?
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Review Questions for lecture 15 - Review Questions for...

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