2. Why would having regulated virulence genes be an advantage to a bacterium?
4. What type of mutation(s) would cause genes regulated by a two-component regulatory to be expressed constitutively?
6. Briefly describe the mechanisms by which Rho-dependent termination occurs.
8. Describe how the regulatory mechanism of “quorum sensing” might play a role in the pathogenesis of a Vibrio infection and how it works using the example of Lux (bacterial luminescence).
10. Bacteria adapt to changes in their environment and alter regulation of gene expression accordingly. One of the mechanisms of regulation in bacteria involves transduction of an environmental signal. Explain the function of bacterial sensors and transducers for gene regulation. How do two-component regulatory systems control gene expression in response to environmental changes? Give examples.
12. You are using a gene fusion between a very bad gene (vbg) and lacZ to study the regulation of vbg by iron. (When lacZ is expressed, cells are blue: when lacZ is not expressed, cells are white.) You introduce a transposon into the strain carrying a vbg-lacZ fusion and screen for regulatory mutants. You conclude that vbg is expressed in the presence of iron because you observe that, for the wildtype fusions, colonies are ________ in the presence of iron and ______ in the absence of iron. You conclude that the transposon has been inserted into a gene encoding the activator protein because you observe that the colonies are __________ in the presence of iron and ________ in the absence of iron.
a. blue…white….blue…blue
b. white…blue….blue…blue
c. blue…white….white…white
d. white…blue….white…white
e. white…blue….white…blue
