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Total Categories: 5
Antisense RNA (asRNA) is a double-stranded DNA molecule primarily responsible for protein synthesis.
Answer: False
The source material defines antisense RNA (asRNA) as a single-stranded RNA molecule, not double-stranded DNA, and its primary role is gene expression regulation, not protein synthesis.
The primary function of antisense RNA is to regulate gene expression by binding to messenger RNA and blocking its translation.
Answer: True
The principal function of antisense RNA is indeed the regulation of gene expression, achieved by hybridizing with target messenger RNA (mRNA) and thereby inhibiting its translation into protein.
What is the primary role of antisense RNA (asRNA) in biological systems?
Answer: To regulate gene expression by blocking mRNA translation.
The principal function of antisense RNA is the regulation of gene expression, achieved by hybridizing with target messenger RNA (mRNA) and thereby inhibiting its translation into protein.
Which of the following is an alternative name for natural antisense RNA?
Answer: Antisense transcript
Natural antisense RNA is also commonly referred to as an antisense transcript or a natural antisense transcript.
According to the source material, antisense RNA is transcribed from which strand of a gene?
Answer: The lagging strand.
The source material indicates that antisense RNA is transcribed from the lagging strand of a gene.
The micF asRNA in Escherichia coli was discovered because it repressed the expression of the outer membrane protein OmpF.
Answer: True
The discovery of the micF asRNA in *Escherichia coli* was linked to its role in repressing the expression of the outer membrane protein OmpF, demonstrating its regulatory function.
Genome-wide searches for small regulatory RNAs and comprehensive transcriptome analysis are modern methods for identifying antisense RNAs.
Answer: True
Contemporary methodologies for identifying antisense RNAs extensively utilize genome-wide searches for small regulatory RNAs and comprehensive transcriptome analyses.
Computational searches for antisense RNAs typically focus on identifying regions with conserved RNA structures and excluding known protein-encoding regions.
Answer: True
Computational strategies for predicting antisense RNAs commonly involve the identification of regions exhibiting conserved RNA structures and the exclusion of established protein-encoding sequences.
A limitation of computational searches is that they always successfully identify antisense RNAs transcribed from the opposite strand of encoding genes.
Answer: False
A significant limitation of computational searches is their tendency to focus on intergenic regions, potentially overlooking antisense RNAs transcribed from the opposite strand of encoding genes.
Oligonucleotide microarrays can be used to detect antisense RNAs that overlap with encoding genes.
Answer: True
Oligonucleotide microarrays represent a viable method for detecting antisense RNAs that are transcribed from the same genomic region as encoding genes.
The discovery of an antisense oligonucleotide inhibiting Rous sarcoma virus replication by Zamecnik and Stephenson occurred in the late 1990s.
Answer: False
The foundational discovery by Zamecnik and Stephenson regarding antisense oligonucleotides inhibiting viral replication occurred in 1978, not the late 1990s.
The discovery of the micF asRNA in E. coli was related to the regulation of which cellular components?
Answer: Outer membrane porin proteins (OmpC/OmpF).
The discovery of the micF asRNA in *E. coli* was associated with its role in regulating the expression of outer membrane porin proteins, specifically OmpF.
How are most antisense RNAs identified in contemporary research?
Answer: Through genome-wide searches and transcriptome analysis.
Contemporary research predominantly identifies antisense RNAs through comprehensive genome-wide searches and detailed transcriptome analyses, moving beyond serendipitous discoveries.
Which of the following is a limitation of computational searches for identifying antisense RNAs?
Answer: They primarily focus on intergenic regions, potentially missing overlapping transcripts.
A notable limitation of computational searches is their frequent emphasis on intergenic regions, which may lead to the omission of antisense RNAs transcribed from the opposite strand of protein-encoding genes.
What method can be used to detect antisense RNAs transcribed from the same region as encoding genes?
Answer: Oligonucleotide microarrays.
Oligonucleotide microarrays are a technique capable of detecting antisense RNAs that overlap with encoding genes, utilizing probes derived from one or both strands of the encoding genes.
What significant discovery in 1978 laid the foundation for antisense RNA as a therapeutic strategy?
Answer: The discovery of an antisense oligonucleotide inhibiting viral replication.
The 1978 discovery by Zamecnik and Stephenson, demonstrating an antisense oligonucleotide's ability to inhibit viral replication, established the foundational concept for antisense RNA as a therapeutic strategy.
Short non-coding RNAs are classified as natural antisense RNAs that are longer than 200 nucleotides.
Answer: False
Natural antisense RNAs are classified by length into short non-coding RNAs, which are less than 200 nucleotides, and long non-coding RNAs, which exceed 200 nucleotides. Therefore, short non-coding RNAs are not longer than 200 nucleotides.
Antisense RNAs can be classified by their genomic location as either cis-acting or trans-acting.
Answer: True
A fundamental classification of antisense RNAs is based on their genomic location relative to their target genes, categorizing them as either cis-acting or trans-acting.
A cis-acting antisense RNA is transcribed from a different genetic locus than its target gene.
Answer: False
A cis-acting antisense RNA is transcribed from the complementary strand of the *same* genetic locus as its target gene, not a different one.
Cis-acting antisense RNAs targeting messenger RNAs primarily function by recruiting chromatin-modifying enzymes.
Answer: False
Cis-acting antisense RNAs that target messenger RNAs primarily function by blocking ribosome binding or recruiting RNAse H for degradation. Recruiting chromatin-modifying enzymes is characteristic of epigenetic regulation, not the primary post-transcriptional mechanism for mRNA-targeting cis-acting asRNAs.
Trans-acting antisense RNAs generally exhibit a high degree of sequence complementarity with their target genes.
Answer: False
Trans-acting antisense RNAs generally display a *lower* degree of sequence complementarity with their targets compared to cis-acting antisense RNAs.
Antisense RNAs regulate gene expression through epigenetic, co-transcriptional, and post-transcriptional mechanisms.
Answer: True
Antisense RNAs modulate gene expression via three principal mechanisms: epigenetic regulation, co-transcriptional regulation, and post-transcriptional regulation.
Some antisense RNAs can silence genes long-term by recruiting DNA methyltransferases to promoter regions.
Answer: True
Certain antisense RNAs can induce long-term gene silencing by recruiting DNA methyltransferases to the promoter regions of target genes, leading to epigenetic modifications.
Antisense RNAs can influence gene expression during transcription by causing RNA polymerase collisions or pausing.
Answer: True
Antisense RNAs can modulate gene expression during the transcription process (co-transcriptionally) by inducing RNA polymerase collisions leading to premature termination or causing polymerase pausing.
Post-transcriptional regulation by antisense RNA occurs before the mRNA molecule is synthesized.
Answer: False
Post-transcriptional regulation by antisense RNA occurs *after* the mRNA molecule has been synthesized, by interacting with the mature mRNA.
How are natural antisense RNAs classified based on their length?
Answer: Short (< 200 nucleotides) and Long (> 200 nucleotides).
Natural antisense RNAs are categorized based on their length into two primary groups: short non-coding RNAs (less than 200 nucleotides) and long non-coding RNAs (greater than 200 nucleotides).
Which of the following is NOT listed as a way to classify antisense RNAs?
Answer: Target protein's cellular function.
Antisense RNAs are classified by genomic location, length, and regulatory mechanism, but not directly by the cellular function of the protein encoded by their target gene.
What defines a cis-acting antisense RNA?
Answer: It is transcribed from the opposite strand of a target gene at the same locus.
A cis-acting antisense RNA is defined by its transcription from the complementary strand of a target gene located at the identical genetic locus.
How do cis-acting antisense RNAs typically regulate gene expression at the post-transcriptional level?
Answer: By blocking ribosome binding to mRNA or recruiting RNAase H for degradation.
Cis-acting antisense RNAs targeting messenger RNAs exert their regulatory function post-transcriptionally by either impeding ribosome binding or recruiting enzymes like RNAse H for mRNA degradation.
Which characteristic distinguishes trans-acting antisense RNAs from cis-acting ones?
Answer: Trans-acting RNAs generally display lower sequence complementarity with targets.
Trans-acting antisense RNAs are distinguished from cis-acting ones by generally exhibiting reduced sequence complementarity with their target genes.
Which of the following is NOT a primary mechanism by which antisense RNAs regulate gene expression?
Answer: Direct protein synthesis from antisense sequences.
Antisense RNAs regulate gene expression through epigenetic, co-transcriptional, and post-transcriptional mechanisms; they do not directly synthesize proteins.
How can antisense RNAs induce gene silencing through DNA methylation?
Answer: By recruiting DNA methyltransferases to gene promoters.
Certain antisense RNAs can induce gene silencing by recruiting DNA methyltransferases to the promoters of target genes, leading to DNA methylation and subsequent transcriptional repression.
What is the function of recruiting Polycomb Repressive Complex 2 (PRC2) by some antisense RNAs?
Answer: To modify histones, leading to gene repression.
Recruitment of Polycomb Repressive Complex 2 (PRC2) by antisense RNAs leads to histone modifications, such as histone methylation, which ultimately results in gene repression.
Which of the following is an example of co-transcriptional regulation by antisense RNA?
Answer: Causing RNA polymerase collisions leading to termination.
Co-transcriptional regulation by antisense RNA can occur when they induce RNA polymerase collisions, leading to premature transcription termination.
Natural antisense RNAs have only been identified in eukaryotic organisms like plants and mammals.
Answer: False
Natural antisense RNAs have been identified in both prokaryotic organisms, such as bacteria and plasmids, and eukaryotic organisms, including plants and mammals.
RNA I, found in the ColE1 plasmid, regulates the plasmid's copy number by forming a duplex with RNA II.
Answer: True
Within the ColE1 plasmid system, RNA I functions as an antisense RNA that modulates the plasmid's copy number by forming a duplex structure with RNA II, a critical replication primer.
In plants like Arabidopsis, antisense RNAs such as COOLAIR regulate gene expression primarily by directly degrading target mRNAs.
Answer: False
In plant species such as *Arabidopsis*, antisense RNAs like COOLAIR primarily regulate gene expression through epigenetic mechanisms involving chromatin modification, rather than direct mRNA degradation.
The XIST antisense RNA in mammalian cells is involved in activating gene expression on the X chromosome.
Answer: False
The XIST antisense RNA in mammalian cells is crucial for X chromosome inactivation, a process that silences gene expression on one of the X chromosomes, not activates it.
The antisense RNA ANRIL is known to activate the tumor suppressor gene p15INK4b in certain types of leukemia.
Answer: False
The antisense RNA ANRIL is known to *silence*, not activate, the tumor suppressor gene p15INK4b in certain types of leukemia, typically through epigenetic mechanisms like DNA methylation.
The ZEB2 asRNA enhances E-cadherin synthesis by promoting the degradation of E-cadherin mRNA.
Answer: False
The ZEB2 asRNA enhances E-cadherin synthesis not by degrading its mRNA, but by maintaining an internal ribosome entry site (IRES) that facilitates efficient translation of the ZEB2 mRNA.
Natural antisense RNAs have been identified in which types of organisms?
Answer: In both prokaryotes and eukaryotes.
Natural antisense RNAs have been identified across a broad spectrum of life, including both prokaryotic organisms (e.g., bacteria, plasmids) and eukaryotic organisms (e.g., plants, mammals).
What is the function of RNA I in the ColE1 plasmid, as described in the source?
Answer: It regulates the plasmid's copy number by interacting with RNA II.
Within the ColE1 plasmid system, RNA I functions as an antisense RNA that modulates the plasmid's copy number by forming a duplex structure with RNA II, a critical replication primer.
In plants like Arabidopsis, how does the antisense RNA COOLAIR primarily regulate the FLC gene?
Answer: Through epigenetic mechanisms involving chromatin modification.
In plants such as *Arabidopsis*, the antisense RNA COOLAIR regulates the FLC gene primarily through epigenetic mechanisms involving chromatin modification, rather than direct mRNA degradation.
What is the role of the XIST antisense RNA in mammalian cells?
Answer: Facilitating X chromosome inactivation.
Within mammalian cells, the XIST antisense RNA is instrumental in the process of X chromosome inactivation, leading to the transcriptional silencing of one X chromosome.
The antisense RNA ANRIL is implicated in silencing the p15INK4b gene in leukemia primarily through which mechanism?
Answer: Inducing DNA methylation of the promoter.
The antisense RNA ANRIL silences the p15INK4b gene in certain leukemias primarily by inducing DNA methylation at the gene's promoter region.
How does the ZEB2 asRNA impact the synthesis of E-cadherin?
Answer: By maintaining an internal ribosome entry site (IRES) for translation.
The ZEB2 asRNA enhances E-cadherin synthesis by preserving an internal ribosome entry site (IRES) within the ZEB2 mRNA, which is critical for efficient translation.
Synthetic antisense RNAs are primarily used in research for gene activation, increasing protein production.
Answer: False
Synthetic antisense RNAs are predominantly employed in research settings for gene knockdown or silencing, rather than for gene activation or enhancing protein production.
Fomivirsen, approved in 1998, was the first FDA-approved antisense RNA drug designed to treat high cholesterol levels.
Answer: False
Fomivirsen, approved in 1998, was indeed the first FDA-approved antisense RNA drug; however, its therapeutic purpose was to treat cytomegalovirus (CMV) retinitis, not high cholesterol levels.
Mipomersen is an antisense oligonucleotide used to manage low-density lipoprotein cholesterol levels in patients with homozygous familial hypercholesterolemia.
Answer: True
Mipomersen is an antisense oligonucleotide approved for the management of low-density lipoprotein cholesterol (LDL) levels, specifically in patients diagnosed with homozygous familial hypercholesterolemia (HoFH).
Mipomersen reduces LDL cholesterol by targeting the mRNA for apolipoprotein B-100, leading to its increased production.
Answer: False
Mipomersen reduces LDL cholesterol by targeting the mRNA for apolipoprotein B-100 for degradation, thereby decreasing its production, not increasing it.
A key advantage of antisense RNAs as therapeutic targets is their broad, non-specific binding across the genome.
Answer: False
A key advantage of antisense RNAs as therapeutic targets is their *high sequence specificity*, not broad, non-specific binding, which minimizes off-target effects.
Developing drugs to increase gene expression is generally considered less challenging than developing inhibitors.
Answer: False
Developing drugs to increase gene expression is generally considered *more* challenging than developing inhibitors, due to the complexity of activating endogenous pathways.
What is a primary application of synthetically produced antisense RNAs in research?
Answer: Gene knockdown or silencing.
Synthetically produced antisense RNAs are widely utilized in research as tools for gene knockdown, a process aimed at reducing or silencing the expression of specific target genes.
What was the therapeutic purpose of fomivirsen, the first FDA-approved antisense RNA drug?
Answer: To combat cytomegalovirus (CMV) retinitis.
Fomivirsen, the first FDA-approved antisense RNA drug, was developed for the treatment of cytomegalovirus (CMV) retinitis, particularly in patients with AIDS.
Mipomersen is an antisense oligonucleotide approved for which medical condition?
Answer: Homozygous familial hypercholesterolemia (HoFH).
Mipomersen has received FDA approval for the management of low-density lipoprotein cholesterol (LDL) levels in individuals with homozygous familial hypercholesterolemia (HoFH).
How does mipomersen exert its therapeutic effect in lowering LDL cholesterol?
Answer: By targeting the mRNA for apolipoprotein B-100 for degradation.
Mipomersen functions by binding to the messenger RNA (mRNA) encoding apolipoprotein B-100, thereby targeting it for degradation and consequently reducing LDL cholesterol levels.
Why are trans-acting antisense RNAs currently considered less viable targets for drug development compared to cis-acting asRNAs?
Answer: They form less stable complexes with targets and may require chaperones.
Trans-acting antisense RNAs form less stable complexes with their targets due to lower complementarity and may require chaperone proteins for function, rendering them currently less viable therapeutic targets than cis-acting asRNAs.
What is a significant challenge related to the intracellular uptake of artificial antisense RNAs?
Answer: They generally have limited ability to enter cells on their own.
Artificial antisense RNAs typically exhibit restricted intrinsic capacity for cellular uptake, posing a significant challenge for their therapeutic application.
What is the therapeutic goal of using antagoNATs (antisense oligonucleotides targeting natural antisense transcripts)?
Answer: To inhibit endogenous antisense RNAs, thereby increasing target gene expression.
The therapeutic objective of antagoNATs is to inhibit endogenous antisense RNAs, consequently alleviating the repression they impose and thereby increasing the expression of targeted genes.
A common chemical modification used to prevent degradation of therapeutic oligonucleotides is the phosphorothioate linkage. What is a potential drawback of this modification?
Answer: It can cause proinflammatory side effects.
While phosphorothioate linkages enhance oligonucleotide stability, they are associated with potential proinflammatory side effects, such as fever and chills.
Off-target toxicity in synthesized antisense oligonucleotides can occur when:
Answer: The oligonucleotide binds to unintended RNA sequences, even with a single mismatch.
Off-target toxicity arises when synthesized oligonucleotides bind to unintended RNA sequences, potentially due to even minor sequence discrepancies that compromise precise target recognition.