Nucleic Acids Biochemistry and Promoter Sequences Quiz

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Questions and Answers

What is the role of Hfq in bacterial small RNA regulation?

Hfq promotes the degradation of sRNAs
Hfq prevents sRNA from binding to mRNA targets
Hfq inhibits the transcription of sRNAs
Hfq helps sRNA bind mRNA target and stabilizes the binding (correct)

What happens when a riboswitch binds to S-adenosylmethionine (SAM)?

It prevents the formation of riboswitch structures
It causes rearrangements in the aptamer and expression platform, affecting gene expression (correct)
It inhibits the binding of uncharged tRNAs
It activates the translation of the gene transcript

How do riboswitches respond to metabolite binding?

They exhibit protein-like structure diversity (correct)
They prevent the formation of riboswitch structures
They increase access to ribosome binding sites
They block any further RNA Polymerase transcription of the transcript

What is the function of regulatory small RNAs (sRNAs) in bacteria?

They can repress levels of one protein and promote another (D) Signup and view all the answers

How do bacterial small RNAs (sRNAs) affect mRNA translation?

They can cause mRNAs destruction by RNase, blocking translation (A) Signup and view all the answers

Riboswitches are only found in eukaryotic cells.

False (B) Signup and view all the answers

Bacterial small RNAs (sRNAs) always repress levels of proteins and never promote them.

False (B) Signup and view all the answers

Riboswitches can bind and respond to uncharged tRNAs.

True (A) Signup and view all the answers

Activated riboswitch structures always block further transcription or translation.

False (B) Signup and view all the answers

Riboswitches exhibit limited structural diversity compared to proteins.

False (B) Signup and view all the answers

Explain the regulatory roles of single stranded RNA in gene transcription and translation.

Single stranded RNA can facilitate regulatory roles by serving as regulators of gene transcription and translation, and small RNAs (sRNAs) can repress levels of one protein and promote another. Signup and view all the answers

Describe the function and mechanism of riboswitches in gene transcripts.

Riboswitches are built-in metabolite sensors that control mRNA translation in response to changes in metabolite amount. They consist of an aptamer region that binds a metabolite and an expression platform that changes conformation in response to metabolite binding. This results in altered transcription, translation, or splicing of RNA. Signup and view all the answers

How do bacterial small RNAs (sRNAs) regulate gene expression and mRNA translation?

Bacterial small RNAs (sRNAs) can regulate gene expression by binding to complementary target mRNAs to form double-stranded RNAs, leading to mRNA destruction by RNase and blocking translation. However, in some cases, sRNAs can also stimulate translation. Signup and view all the answers

Explain the mechanism of attenuation and its effect on RNA Pol transcription and ribosomal translation.

Attenuation causes RNA Pol dissociation, blocking any further RNA Polymerase transcription of the transcript. It can also block ribosomal translation of the transcript by preventing initiation through the formation of a structure with the ribosome binding site (RBS). Signup and view all the answers

How do riboswitches respond to metabolite binding and what are the different outcomes of metabolite binding to riboswitches?

Riboswitches respond to metabolite binding by undergoing conformational changes, which can either activate or prevent transcription termination, block or increase access to ribosome binding site, and alter ribosome interactions. They can bind and respond to various metabolites, each with unique structures. Signup and view all the answers

Study Notes

Eukaryotic Promoters and Transcription Initiation

Eukaryotic promoters contain subsets of four different sequences
Prokaryotic σ factor replaced by many eukaryotic general transcription factors (GTFs) that assist RNA polymerase
Prereplicative complex involves sequential TFII assembly followed by phosphorylation events
Eukaryotic RNA polymerase II targeted by multiple protein kinases for promoter escape

Mediator Complexes and RNA Polymerase II Activity

Multisubunit Mediator complexes generally needed for RNA polymerase activity
RNA polymerase II phosphorylation serves as a switch between initiation and elongation

Elongation and Processing

Elongation factor proteins accelerate RNA growth by stopping pauses (errors)
FACT-mediated reversible histone removal and replacement keeps DNA packed and protected
Proper elongation, termination, and processing require enzyme recruitment
RNA capped early to protect transcript and ensure proper processing
RNA 5’ capping needs GTP, S-adenosyl methionine (SAdoMet), and three sequential enzymes
RNA’s poly-A tail partly encoded by DNA, RNA cleaved, and enzymes add extra A

Transcriptional Termination

Transcriptional termination models differ in that one needs RNase (torpedo)

RNA Polymerase I and III

RNA genes transcribing RNA polymerase I and III require specialized GTFs

Regulatory RNAs

Regulatory RNAs exploit Watson-Crick base-pairing to other RNAs and DNAs, blocking binding and altering RNA structure

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Description

Test your knowledge of nucleic acids biochemistry, regulatory RNAs, and examples of prokaryotic and eukaryotic promoters with this quiz. Review the concepts of eukaryotic promoter sequences, the role of sigma factors and general transcription factors, as well as the process of pre-replicative complex assembly and promoter escape.