MicroRNA Biogenesis Quiz

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Questions and Answers

What is the function of miRNAs?

They activate transposons

They inhibit gene expression by binding to mRNA (correct)

They promote gene expression by binding to mRNA

They degrade RNA polymerase II

What is the precursor of miRNA called?

pro-miRNA

pre-mRNA

pre-pro-miRNA

pri-miRNA (correct)

What is the function of the microprocessor complex in miRNA biogenesis?

It cleaves the loop from the hairpin structure

It catalyzes the production of pre-miRNA from pri-miRNA (correct)

It loads mature miRNA onto the RNA-induced silencing complex

It exports pre-miRNA from the nucleus to the cytoplasm

What is the role of Exportin 5 in miRNA biogenesis?

It exports pre-miRNA from the nucleus to the cytoplasm Signup and view all the answers

What is the function of Dicer in miRNA biogenesis?

It cleaves the loop from the hairpin structure, producing a short double-stranded RNA with two overhangs Signup and view all the answers

What is the function of the RNA-induced silencing complex (RISC)?

It inhibits translation or degrades the target mRNA Signup and view all the answers

What is the consequence of miRNA dysregulation?

It is implicated in diseases such as cancer and neurological disorders Signup and view all the answers

What is the function of microRNAs?

To bind to mRNA and inhibit translation or degrade the target mRNA Signup and view all the answers

What is the precursor of miRNA called?

Pri-miRNA Signup and view all the answers

What is the name of the complex that catalyzes the production of pre-miRNA from pri-miRNA in the nucleus?

Drosha and DGCR8 Signup and view all the answers

What is the role of Exportin 5 (XPO5) in the biogenesis of miRNA?

To export pre-miRNA from the nucleus into the cytoplasm Signup and view all the answers

What is the name of the enzyme that cleaves the loop from the hairpin structure, producing a short double-stranded RNA with two overhangs at both 3' termini, which contains the future mature miRNA?

Dicer Signup and view all the answers

What is the name of the complex onto which the mature miRNA is loaded, which inhibits translation or degrades the target mRNA?

RNA-induced silencing complex (RISC) Signup and view all the answers

What is the name of the RNA polymerase that transcribes miRNA genes?

RNA polymerase II Signup and view all the answers

What is the primary level at which gene expression is regulated?

Transcription initiation Signup and view all the answers

What determines whether a gene is transcribed?

The presence of specific gene regulatory sequences and regulatory proteins Signup and view all the answers

What are enhancers and what is their function?

Modular elements located more distal to the transcription start site that control the activity of a promoter from various locations Signup and view all the answers

What are the common structural motifs found in DNA-binding proteins?

Helix-turn-helix, zinc fingers, leucine zipper, and helix-loop-helix Signup and view all the answers

What is promoter proximal pausing?

A regulatory mechanism that occurs after RNA polymerase II recruitment at the promoter Signup and view all the answers

What are negative elongation factors and what is their role in transcription?

Proteins that bind to RNA polymerase II and prevent it from proceeding Signup and view all the answers

What are positive transcription elongation factors (PTEF-b) and how are they activated?

Proteins that can reactivate RNA polymerase II through phosphorylation, and they are activated by transcription factors (TFs) Signup and view all the answers

Why is regulation by promoter proximal pausing important for genes involved in development and response to stimuli?

It allows for precise control of gene expression Signup and view all the answers

Which of the following is a structural motif found in DNA-binding proteins?

Leucine zipper Signup and view all the answers

What is the role of enhancers in gene expression?

They regulate the activity of a promoter Signup and view all the answers

What is promoter proximal pausing?

A regulatory mechanism that occurs after RNA polymerase II recruitment at the promoter Signup and view all the answers

Which of the following is a transcription factor that requires a ligand to become activated?

Estrogen receptor Signup and view all the answers

What is the function of positive transcription elongation factors (PTEF-b)?

To reactivate RNA polymerase II through phosphorylation Signup and view all the answers

What is the role of heterodimers in transcription factor regulation?

To increase the number of functional TFs Signup and view all the answers

What is the importance of regulation by promoter proximal pausing?

It is important for genes involved in development and response to stimuli Signup and view all the answers

What is the role of specific transcription factors in gene expression?

To recognize and bind precise nucleotide sequences to regulate the activity of genes Signup and view all the answers

Study Notes

Biogenesis of MicroRNA

Double-stranded RNA inhibits gene expression via RNA interference (RNAi)
RNAi is conserved in all eukaryotes and regulates endogenous genes, transposon silencing, and pathogen defense in plants
MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression by binding to mRNA and inhibiting translation or degrading the target mRNA
miRNAs are involved in various biological processes, including development, differentiation, and immune response, and their dysregulation is implicated in diseases such as cancer and neurological disorders
miRNAs are encoded by endogenous genes and transcribed by RNA polymerase II
miRNA genes are regulated by transcription factors and enhancers and are sensitive to chromatin status
miRNA precursors are long RNAs called pri-miRNA that contain a self-complementary region that forms a hairpin structure
The microprocessor complex, including Drosha and DGCR8, catalyzes the production of pre-miRNA from pri-miRNA in the nucleus
Pre-miRNA is exported from the nucleus into the cytoplasm by Exportin 5 (XPO5)
In the cytoplasm, Dicer cleaves the loop from the hairpin structure, producing a short double-stranded RNA with two overhangs at both 3' termini, which contains the future mature miRNA
Dicer recognizes the base of pre-miRNA and its loop, allowing for correct positioning within the catalytic site
The mature miRNA is loaded onto the RNA-induced silencing complex (RISC), which inhibits translation or degrades the target mRNA

Biogenesis of MicroRNA

Double-stranded RNA inhibits gene expression via RNA interference (RNAi)
RNAi is conserved in all eukaryotes and regulates endogenous genes, transposon silencing, and pathogen defense in plants
MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression by binding to mRNA and inhibiting translation or degrading the target mRNA
miRNAs are involved in various biological processes, including development, differentiation, and immune response, and their dysregulation is implicated in diseases such as cancer and neurological disorders
miRNAs are encoded by endogenous genes and transcribed by RNA polymerase II
miRNA genes are regulated by transcription factors and enhancers and are sensitive to chromatin status
miRNA precursors are long RNAs called pri-miRNA that contain a self-complementary region that forms a hairpin structure
The microprocessor complex, including Drosha and DGCR8, catalyzes the production of pre-miRNA from pri-miRNA in the nucleus
Pre-miRNA is exported from the nucleus into the cytoplasm by Exportin 5 (XPO5)
In the cytoplasm, Dicer cleaves the loop from the hairpin structure, producing a short double-stranded RNA with two overhangs at both 3' termini, which contains the future mature miRNA
Dicer recognizes the base of pre-miRNA and its loop, allowing for correct positioning within the catalytic site
The mature miRNA is loaded onto the RNA-induced silencing complex (RISC), which inhibits translation or degrades the target mRNA

Regulation of Gene Expression: Transcription Factors and Enhancers

Gene expression is regulated primarily at the level of transcription initiation.
Transcription initiation depends on the accessibility of the gene within open chromatin and the presence of specific gene regulatory sequences and regulatory proteins that recruit RNA polymerase.
The accessibility of the gene within open chromatin is a prerequisite for transcription initiation.
The presence of specific gene regulatory sequences and the availability of regulatory proteins that recruit RNA polymerase determine whether a gene is transcribed.
Enhancers are modular elements located more distal to the transcription start site and contain binding sites for specific transcription factors.
Enhancers determine the efficiency and specificity of transcription initiation, controlling the activity of a promoter from various locations, independently of their orientation.
Specific transcription factors are proteins that recognize and bind precise nucleotide sequences to regulate the activity of genes and determine where and when a gene is transcribed.
Transcription factors function in a combinatorial, cooperative, and synergistic manner to regulate gene expression.
Enhancers stimulate the transcription of genes and their activity can be measured using a synthetic gene with a reporter gene.
Helix-turn-helix, zinc fingers, leucine zipper, and helix-loop-helix are common structural motifs found in DNA-binding proteins.
Heterodimers increase the number of functional TFs and opportunities for combinatorial control of gene expression.
The estrogen receptor is a transcription factor that requires a ligand to become activated and its activation leads to the transcription of target genes.Understanding Promoter Proximal Pausing in Transcription
Promoter proximal pausing is a regulatory mechanism that occurs after RNA polymerase II recruitment at the promoter.
RNA polymerase II is phosphorylated during promoter clearance, and transcription proceeds until a block occurs when the transcript reaches the 20-40 nucleotides long mark.
Negative elongation factors bind to RNA polymerase II and prevent it from proceeding.
Positive transcription elongation factors (PTEF-b) can reactivate RNA polymerase II through phosphorylation.
PTEF-b is located in the nucleus, close to the promoter and needs to be released and activated by transcription factors (TFs) to reactivate stalled RNA polymerase II.
TFs can either contact PTEF-b directly or through a mediator to promote the release of inhibitory complexes and activate PTEF-b.
Regulation by promoter proximal pausing is important for genes involved in development and response to stimuli.
Examples of genes regulated by promoter proximal pausing are those encoding heat shock proteins in Drosophila and target genes of hypoxia-inducible factors (HIF).
Heat shock factor is activated in response to excessive heat and can unlock RNA polymerase II, promoting the release of paused RNA polymerase II and production of heat shock proteins.
HIFs stabilize under low oxygen conditions, bind to regulatory elements of their target genes, and promote the release of paused RNA polymerase II, allowing the production of proteins required for cell survival in hypoxic environments.
PTEF-b needs to be released and activated by transcription factors to reactivate stalled RNA polymerase II.
Regulation by promoter proximal pausing is important for genes involved in development and response to stimuli, such as heat shock proteins and HIFs target genes.

Regulation of Gene Expression: Transcription Factors and Enhancers

Gene expression is regulated primarily at the level of transcription initiation.
Transcription initiation depends on the accessibility of the gene within open chromatin and the presence of specific gene regulatory sequences and regulatory proteins that recruit RNA polymerase.
The accessibility of the gene within open chromatin is a prerequisite for transcription initiation.
The presence of specific gene regulatory sequences and the availability of regulatory proteins that recruit RNA polymerase determine whether a gene is transcribed.
Enhancers are modular elements located more distal to the transcription start site and contain binding sites for specific transcription factors.
Enhancers determine the efficiency and specificity of transcription initiation, controlling the activity of a promoter from various locations, independently of their orientation.
Specific transcription factors are proteins that recognize and bind precise nucleotide sequences to regulate the activity of genes and determine where and when a gene is transcribed.
Transcription factors function in a combinatorial, cooperative, and synergistic manner to regulate gene expression.
Enhancers stimulate the transcription of genes and their activity can be measured using a synthetic gene with a reporter gene.
Helix-turn-helix, zinc fingers, leucine zipper, and helix-loop-helix are common structural motifs found in DNA-binding proteins.
Heterodimers increase the number of functional TFs and opportunities for combinatorial control of gene expression.
The estrogen receptor is a transcription factor that requires a ligand to become activated and its activation leads to the transcription of target genes.Understanding Promoter Proximal Pausing in Transcription
Promoter proximal pausing is a regulatory mechanism that occurs after RNA polymerase II recruitment at the promoter.
RNA polymerase II is phosphorylated during promoter clearance, and transcription proceeds until a block occurs when the transcript reaches the 20-40 nucleotides long mark.
Negative elongation factors bind to RNA polymerase II and prevent it from proceeding.
Positive transcription elongation factors (PTEF-b) can reactivate RNA polymerase II through phosphorylation.
PTEF-b is located in the nucleus, close to the promoter and needs to be released and activated by transcription factors (TFs) to reactivate stalled RNA polymerase II.
TFs can either contact PTEF-b directly or through a mediator to promote the release of inhibitory complexes and activate PTEF-b.
Regulation by promoter proximal pausing is important for genes involved in development and response to stimuli.
Examples of genes regulated by promoter proximal pausing are those encoding heat shock proteins in Drosophila and target genes of hypoxia-inducible factors (HIF).
Heat shock factor is activated in response to excessive heat and can unlock RNA polymerase II, promoting the release of paused RNA polymerase II and production of heat shock proteins.
HIFs stabilize under low oxygen conditions, bind to regulatory elements of their target genes, and promote the release of paused RNA polymerase II, allowing the production of proteins required for cell survival in hypoxic environments.
PTEF-b needs to be released and activated by transcription factors to reactivate stalled RNA polymerase II.
Regulation by promoter proximal pausing is important for genes involved in development and response to stimuli, such as heat shock proteins and HIFs target genes.

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Description

Test your knowledge on the biogenesis of microRNA with this quiz! Learn about the process of how miRNAs are produced, regulated, and function in different biological processes. From the microprocessor complex to the RNA-induced silencing complex, this quiz covers all the essential details of miRNA biogenesis. Challenge yourself and see how much you know about this important regulatory mechanism in gene expression!