Regulation of prokaryotic transcription
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Questions and Answers

What is the function of the σ factor in prokaryotic RNA polymerase?

  • To translate mRNA into protein
  • To unwind double-stranded DNA
  • To facilitate DNA recognition and RNA synthesis (correct)
  • To synthesize mRNA

    • What is the role of the up element in bacterial promoter structure?

  • To enhance binding of RNA polymerase to the promoter region (correct)
  • To recruit σ factor
  • To bind RNA polymerase
  • To unwind double-stranded DNA

    • What is the mechanism of action of 6S RNA in regulating RNA polymerase activity?

  • By unwinding double-stranded DNA
  • By facilitating RNA synthesis
  • By inhibiting σ factor activity
  • By forming a 1:1 complex with RNA polymerase holoenzyme (correct)

    • What is the function of anti-σ factors in prokaryotic RNA polymerase?

    <p>To inhibit σ factor activity</p> Signup and view all the answers

    What is the mechanism of action of MerR-type activators?

    <p>By interacting with domain 4 of the σ subunit</p> Signup and view all the answers

    What is the mechanism of repression by steric hindrance?

    <p>By blocking recognition of the promoter by RNA polymerase holoenzyme</p> Signup and view all the answers

    What is the function of AsiA protein in phage T4?

    <p>To redirect RNA polymerase holoenzyme to phage genes</p> Signup and view all the answers

    What is the role of the discriminator element in bacterial promoter structure?

    <p>To recognize promoter elements</p> Signup and view all the answers

    What is the function of SoxS in E. coli?

    <p>To target RNA polymerase holoenzyme to promoters with upstream Sox-box sequences</p> Signup and view all the answers

    What is the mechanism of action of appropriators in phage T4?

    <p>By redirecting RNA polymerase holoenzyme to phage genes</p> Signup and view all the answers

    What is the primary function of the σ54 family of sigma factors?

    <p>To require activation by a class of ATP-dependent activators</p> Signup and view all the answers

    What is the role of the σ subunit in prokaryotic RNA polymerase?

    <p>To facilitate DNA recognition and promoter binding</p> Signup and view all the answers

    How do phages regulate RNA polymerase activity?

    <p>By inducing conformational changes to block σ70's access to template DNA</p> Signup and view all the answers

    What is the effect of 6S RNA on RNA polymerase activity?

    <p>It decreases the number of RNA polymerase molecules</p> Signup and view all the answers

    What is the role of the α CTD subunit in prokaryotic RNA polymerase?

    <p>To bind to the up element of bacterial promoters</p> Signup and view all the answers

    What is the mechanism of action of Class I activators?

    <p>They bind upstream of the promoter and make direct interaction with α CTD</p> Signup and view all the answers

    What is the role of the extended -10 element in bacterial promoter structure?

    <p>It is essential for the formation of open complexes</p> Signup and view all the answers

    What is the effect of anti-σ factors on σ factor activity?

    <p>They stabilize the σ factor and make it incompatible with RNA polymerase</p> Signup and view all the answers

    What is the role of the discriminator element in bacterial promoter structure?

    <p>It is involved in the recognition of promoter elements by RNA polymerase</p> Signup and view all the answers

    What is the mechanism of action of MerR-type activators?

    <p>They realign the -10 element and -35 element to allow RNA polymerase binding</p> Signup and view all the answers

    What is the function of the σ70 family of sigma factors in prokaryotic RNA polymerase?

    <p>Housekeeping sigma factors that do not require activation</p> Signup and view all the answers

    What is the effect of AsiA protein on RNA polymerase activity in phage T4?

    <p>It inhibits the activity of host RNA polymerase to favour phage gene transcription</p> Signup and view all the answers

    What is the mechanism of action of repression by DNA looping?

    <p>Repressor binds to a distal site and loops back to the promoter to block RNA polymerase binding</p> Signup and view all the answers

    What is the function of 6S RNA in regulating RNA polymerase activity?

    <p>It inhibits RNA polymerase activity by binding to the holoenzyme</p> Signup and view all the answers

    What is the function of Class II repressors in prokaryotic RNA polymerase?

    <p>They bind downstream of the promoter and interact with the σ subunit</p> Signup and view all the answers

    What is the function of the α NTD subunit in prokaryotic RNA polymerase?

    <p>It binds to the up element of DNA</p> Signup and view all the answers

    What is the mechanism of action of appropriators in phage regulation?

    <p>They redirect the host RNA polymerase to transcribe phage genes</p> Signup and view all the answers

    What is the function of the σ subunit in prokaryotic RNA polymerase?

    <p>It facilitates DNA recognition and promoter binding</p> Signup and view all the answers

    What is the mechanism of action of anti-repression?

    <p>Binding of a secondary activator to counteract the inhibitory effects of a repressor</p> Signup and view all the answers

    What is the function of the core enzyme in prokaryotic RNA polymerase?

    <p>It catalyses RNA synthesis but not promoter recognition</p> Signup and view all the answers

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