Lecture 36: Other prokaryotic controls
Note: Transcriptional changes caused by production of alternative sigma factors during sporulation in Bacillus subtilis were described in the Lecture 36 notes, but not included in chapter 18 of the textbook. For anyone who may wish to pursue the topic in greater detail, these changes are described on pages 568-569 in Chapter 20 of the textbook.
1. Describe two totally different prokaryotic situations in which replacement of sigma factors is used to activate the transcription of different genes.
2. Describe a prokaryotic viral infection in which a mechanism that does not involve sigma factors is used to alter transcriptional specificity.
3. Describe a mechanism that allows a bacterial virus to shift sequentially from transcription of early genes to transcription of middle genes and then to transcription of late genes.
4. How has antisense technology been put to practical use?
5. What is antitermination, and how is it used to control gene expression? What objective is usually achieved through the use of an antitermination mechanism.
6. Describe the major steps that are required for initiation of the lysogenic state in bacteriophage lambda.
7. How is production of the lambda repressor maintained once it has been initiated?
8. What mechanism is responsible for reversion from the lysogenic state to an active lytic infection in bacteriophage lambda?
9. What causes the plaques produced by an infection with wild-type bacteriophage lambda to be somewhat cloudy?
10. Summarize the molecular competition that ultimately determines whether bacteriophage lambda becomes lysogenic or lytic.
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