Nucleic Acids Biochemistry and Promoter Sequences Quiz

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Questions and Answers

Explain the difference between eukaryotic and prokaryotic promoters in terms of their sequences and protein factors involved in transcription initiation.

Eukaryotic promoters contain subsets of four different sequences and use many eukaryotic GTFs, while prokaryotic promoters are recognized by a σ factor and assist RNA Pol.

What is the role of TATA-binding protein (TBP) in transcription initiation?

TATA-binding protein (TBP) bends the DNA minor groove flat with a β-sheet to assist in RNA Pol II recruitment and chromatin unwinding for transcription initiation.

How do elongation factor proteins contribute to transcriptional elongation?

Elongation factor proteins accelerate RNA growth by stopping pauses and errors during transcriptional elongation.

Explain the process of RNA 5’ capping and its significance in transcription.

<p>RNA is capped early to protect the transcript and ensure proper processing, involving GTP, SAdoMet, and three sequential enzymes.</p> Signup and view all the answers

What is the role of multisubunit Mediator complexes in RNA Pol activity?

<p>Multisubunit Mediator complexes are generally needed for RNA Pol activity and serve as a bridge between transcription factors and RNA Pol II.</p> Signup and view all the answers

What is the role of small RNAs (sRNAs) in bacterial gene regulation and how do they exert their effects?

<p>sRNAs in bacteria can serve to repress levels of one protein and promote another. They regulate gene expression by binding to complementary target mRNAs to form double-stranded RNAs, causing mRNA destruction by RNase and blocking translation. sRNAs can also stimulate translation in some cases.</p> Signup and view all the answers

How does the σ S factor play a role in bacterial gene regulation during stationary phase?

<p>During stationary phase in bacteria, the alternative σ S factor is made and outcompetes the σ 70 subunit. This promotes the transcription of survival proteins. σ S factor translation is affected by mRNA-sRNA binding, either stimulated or inhibited.</p> Signup and view all the answers

What is the role of Hfq in bacterial mRNA translation regulation by small RNAs (sRNAs)?

<p>Hfq, a RNA chaperone protein, helps sRNA bind to mRNA target. It aids in the binding of short, imperfect matching mRNA-sRNA and stabilizes it. Additionally, Hfq can activate translation by binding and removing a RBS-blocking RNA region.</p> Signup and view all the answers

How do riboswitches control gene expression through changes in secondary structure?

<p>Riboswitches are gene transcripts that directly sense metabolite concentration changes. They act as &quot;built-in&quot; metabolite sensors using RNA sequences to control gene expression. Riboswitches can alter their secondary structure in response to metabolite binding, thereby influencing gene expression.</p> Signup and view all the answers

What are the regulatory functions of regulatory RNAs in bacteria?

<p>Regulatory RNAs in bacteria alter RNA structure, recruit proteins, and can enzymatically alter to 'mature' RNAs. They also bind proteins and metabolites to alter metabolism, regulate gene expression, and control transcription through mechanisms such as sRNA-mRNA binding, ribosome blocking, and mRNA destruction.</p> Signup and view all the answers

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