RNA Interference and microRNA Biogenesis Quiz

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Questions and Answers

What is the term used for RNAs that were previously considered 'junk DNA' but are now known to serve as templates for non-protein coding RNAs?

non-coding RNAs (ncRNAs)

What is the major regulatory mechanism in eukaryotes that involves very short RNAs repressing or silencing genes with homology to these short RNAs?

RNA interference (RNAi)

What can RNA interference (RNAi) cause in terms of gene expression inhibition?

inhibition of translation of gene (blocks ribosome), 2) dsRNA formation and then destruction of dsRNA, 3) short RNA binding to gene’s promoter and block it

How can regulatory RNA knowledge be utilized experimentally?

To alter gene transcriptional activity and study gene function, for medical purposes Signup and view all the answers

What did early work on gene regulation propose and what was lacking until the early 1990s?

Early work proposed a role for regulatory RNAs but evidence was lacking until the early 1990s Signup and view all the answers

What was originally predicted about eukaryotes in terms of protein-coding genes based on genome size, and what was later found by genome analysis?

Eukaryotes were originally predicted to have far more protein-coding genes based on genome size but were later found by genome analysis to have far fewer proteins Signup and view all the answers

What do eukaryotes have that can repress or silence genes with homology to them, and what is this mechanism called?

Eukaryotes have very short RNAs that can repress / silence genes that have homology to these short RNAs. This mechanism is called RNA interference (RNAi) Signup and view all the answers

How are very short RNAs made from longer dsRNAs, and what specific process is involved?

These very short RNAs are made from longer dsRNAs by specific enzymes Signup and view all the answers

What can very short RNAs do to gene transcription and translation, and what is the term used for these RNAs?

RNAs can serve as regulators of gene transcription and translation. These RNAs are known as regulatory RNAs. Signup and view all the answers

What is now known to have regulatory roles and can be exploited for experimental alteration of gene transcriptional activity for study and medical purposes?

Non-coding RNAs (ncRNAs) are now known to have regulatory roles and can be exploited for experimental alteration of gene transcriptional activity for study and medical purposes Signup and view all the answers

What are the components of the microprocessor complex for microRNA biogenesis?

DGCR8, Drosha, and Pasha Signup and view all the answers

What is the function of Drosha in microRNA biogenesis?

Drosha cleaves pri-mRNA to yield pre-mRNA containing upper stem + loop Signup and view all the answers

What is the role of Dicer in miRNA production?

Dicer is the second RNA-cleaving enzyme involved in miRNA production and recognizes the Drosha-cleaved pre-miRNA to cleave off the terminal loop Signup and view all the answers

Which protein in the RISC complex acts as the 'slicer'?

Argonaute protein Signup and view all the answers

How are siRNAs made and how do they differ from miRNAs?

siRNAs are made from longer dsRNAs and do not require Drosha, unlike miRNAs Signup and view all the answers

What is the proposed function of RNAi in evolution?

RNAi likely evolved as an ancient immune system used for gene regulation and may have been recruited for use with miRNAs to regulate gene expression Signup and view all the answers

How can RNAi be manipulated for gene regulation purposes?

RNAi can be exploited to artificially silence target genes Signup and view all the answers

How do plants use RNAi to combat viruses?

Plants use RNAi to suppress viral genes by spreading siRNAs made from the viral genome Signup and view all the answers

How have viruses developed countermeasures against RNAi?

Viruses have retaliated by producing anti-RNAi proteins to counteract the RNAi defense mechanism Signup and view all the answers

What is the role of RNAs in gene regulation, and how does RNAi utilize this mechanism?

RNAs can serve as regulators of gene transcription and translation, and RNAi uses very short RNAs to bind and shut off matching regions in target genes Signup and view all the answers

What are the three main classes of small RNAs in eukaryotes?

MicroRNAs (miRNAs), Small interfering RNAs (siRNAs), Repeat-associated small interfering RNAs (rasiRNAs) Signup and view all the answers

What is the function of MicroRNAs (miRNAs)?

They usually downregulate RNAs by translational repression and mRNA decay. Signup and view all the answers

What is the function of Small interfering RNAs (siRNAs)?

They target RNAs for degradation, serving as a cellular defense mechanism. Signup and view all the answers

What are Repeat-associated small interfering RNAs (rasiRNAs) derived from?

They are derived from repetitive regions of the genome and downregulate transcription from repetitive regions. Signup and view all the answers

What is the role of Argonaute-family proteins in eukaryotic sRNA regulation?

They facilitate interactions with targets and are involved in matching interfering RNA with target in mRNA or genome. Signup and view all the answers

What is the role of RNA-Induced Silencing Complex (RISC) in gene expression suppression?

RISC can denature the RNA and allow it to bind to matching regions, causing mRNA destruction or inhibiting translation. Signup and view all the answers

What is the characteristic structure of genetically-encoded micro RNAs (miRNAs)?

Each pre-miRNA is composed of 2 “arms” on either side of the hairpin’s loop within the primary miRNA. Signup and view all the answers

What is the function of DICER in miRNA processing?

DICER liberates the mature miRNA sequences through a second RNase cleavage reaction. Signup and view all the answers

What is the role of the “seed region” in miRNAs?

The “seed region” (bases 2-9) has high complementarity to target RNA and can help identify targets. Signup and view all the answers

What is the function of Drosha/DGCR8 in miRNA processing?

They recognize pre-miRNA structures and help in the nucelolytic processing of miRNAs. Signup and view all the answers

Study Notes

RNA Interference and microRNA Biogenesis

DGCR8, Drosha, and Pasha form the microprocessor complex for microRNA biogenesis
Drosha cleaves pri-mRNA to yield pre-mRNA containing upper stem + loop
Dicer is the second RNA-cleaving enzyme involved in miRNA production
Dicer recognizes the Drosha-cleaved pre-miRNA and cleaves off the terminal loop
Argonaute protein is the 'slicer' protein in the RISC complex, which pairs miRNA & target mRNA for silencing
siRNAs are made from longer dsRNAs and do not require Drosha
RNAi likely evolved as an ancient immune system used for gene regulation
The RNAi machinery may have been recruited for use with miRNAs to regulate gene expression
RNAi can be exploited to artificially silence target genes
Plants use RNAi to suppress viral genes by spreading siRNAs made from the viral genome
Viruses have retaliated by producing anti-RNAi proteins to counteract the RNAi defense mechanism
RNAs can serve as regulators of gene transcription and translation, and RNAi uses very short RNAs to bind and shut off matching regions in target genes

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Description

Test your knowledge of RNA interference and microRNA biogenesis with this quiz. Explore the molecular mechanisms involved in miRNA production, the role of key proteins such as Dicer and Argonaute, and the potential applications and evolutionary significance of RNAi.