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What is the fundamental definition of transcription?
Answer: The process where a segment of DNA is copied into RNA.
Transcription is the fundamental biological process by which a segment of DNA is copied into a complementary RNA molecule. This RNA molecule serves as a template for protein synthesis (mRNA) or functions directly as a non-coding RNA (ncRNA).
Which nucleotide is found in RNA transcripts but not typically in DNA?
Answer: Uracil (U)
During transcription, the RNA complement produced uses the nucleotide uracil (U) in all instances where thymine (T) would typically be found in a DNA complement. This substitution is a key difference between DNA and RNA.
What enzyme carries out transcription?
Answer: RNA Polymerase
RNA polymerase is the enzyme responsible for reading a DNA sequence and synthesizing a complementary RNA strand, known as the primary transcript. It moves along the DNA template strand from the 3' to the 5' direction.
In which direction does RNA polymerase read the DNA template strand during transcription?
Answer: 3' to 5'
RNA polymerase reads the DNA template strand in the 3' to 5' direction. This antiparallel reading allows for the synthesis of the RNA molecule in the 5' to 3' direction.
What is the 'coding strand' in transcription?
Answer: The DNA strand with a sequence identical to the RNA transcript (except T for U).
The coding strand, also known as the non-template strand, possesses a sequence that is nearly identical to the newly synthesized RNA transcript, with the exception that thymine (T) in DNA is replaced by uracil (U) in RNA. The template strand, conversely, is the DNA strand that is read by RNA polymerase to synthesize the RNA.
The coding strand, also known as the template strand, has a sequence identical to the newly synthesized RNA transcript.
Answer: False
The coding strand, also referred to as the non-template strand, possesses a sequence that is nearly identical to the newly synthesized RNA transcript, with the exception that thymine (T) in DNA is replaced by uracil (U) in RNA. The template strand, conversely, is the DNA strand that is read by RNA polymerase to synthesize the RNA.
The four main stages of transcription are initiation, promoter binding, elongation, and termination.
Answer: False
Transcription is generally divided into four main stages: initiation, promoter escape, elongation, and termination. Promoter binding is an integral part of initiation, but promoter escape is often considered a distinct step following initial binding and synthesis.
DNA contains ribose sugar, while RNA contains deoxyribose sugar.
Answer: False
The primary difference between DNA and RNA lies in their sugar component. DNA contains deoxyribose sugar, which lacks an oxygen atom on the second carbon, while RNA contains ribose sugar, which has a hydroxyl group on the second carbon.
The primary transcript synthesized during transcription is always messenger RNA (mRNA) destined to encode proteins.
Answer: False
Transcription produces a primary RNA transcript, which can be messenger RNA (mRNA) destined for protein synthesis, or it can be a non-coding RNA (ncRNA) with various functional roles within the cell.
Compared to DNA replication, transcription generally has:
Answer: Lower fidelity due to fewer proofreading mechanisms.
Transcription generally exhibits lower copying fidelity than DNA replication. This is attributed to the fact that RNA polymerase possesses fewer and less robust proofreading mechanisms compared to DNA polymerase, and RNA errors are typically transient and do not alter the genome.
What is the main difference in the sugar component between DNA and RNA?
Answer: DNA has deoxyribose, RNA has ribose.
The primary difference between DNA and RNA lies in their sugar component. DNA contains deoxyribose sugar, which lacks an oxygen atom on the second carbon, while RNA contains ribose sugar, which has a hydroxyl group on the second carbon.
Transcription generally exhibits higher copying fidelity than DNA replication due to extensive proofreading mechanisms.
Answer: False
Transcription generally exhibits lower copying fidelity than DNA replication. This is attributed to the fact that RNA polymerase possesses fewer and less robust proofreading mechanisms compared to DNA polymerase, and RNA errors are typically transient and do not alter the genome.
What is the main difference in the sugar component between DNA and RNA?
Answer: DNA has deoxyribose, RNA has ribose.
The primary difference between DNA and RNA lies in their sugar component. DNA contains deoxyribose sugar, which lacks an oxygen atom on the second carbon, while RNA contains ribose sugar, which has a hydroxyl group on the second carbon.
Transcription requires an RNA primer to initiate RNA synthesis, similar to DNA replication.
Answer: False
Unlike DNA replication, which requires an RNA primer synthesized by primase to initiate DNA synthesis, transcription is directly initiated by RNA polymerase binding to the promoter sequence without the need for a primer.
In eukaryotes, the preinitiation complex for RNA polymerase II includes TFIIA, TFIIB, TFIID, TFIIE, TFIIF, and TFIIH.
Answer: True
The formation of the preinitiation complex (PIC) for RNA polymerase II in eukaryotes involves the sequential assembly of general transcription factors (GTFs) such as TFIIA, TFIIB, TFIID (containing TBP), TFIIE, TFIIF, and TFIIH, along with RNA polymerase II itself at the promoter.
Abortive initiation occurs when RNA polymerase successfully synthesizes a full-length transcript and escapes the promoter on the first attempt.
Answer: False
Abortive initiation is a phenomenon where RNA polymerase repeatedly synthesizes short, truncated RNA transcripts without successfully escaping the promoter. This process continues until a transcript of sufficient length is produced, allowing promoter escape.
DNA scrunching is a mechanism proposed to help RNA polymerase break its interactions with the promoter during initiation.
Answer: True
DNA scrunching is a proposed mechanism where the DNA is unwound and distorted within the RNA polymerase during transcription initiation. This process is thought to provide the necessary energy to break the interactions between the RNA polymerase and the promoter, facilitating promoter escape.
In bacteria, the sigma factor is essential for recognizing promoter sequences and initiating transcription.
Answer: True
In bacteria, the sigma factor binds to RNA polymerase, forming a holoenzyme that specifically recognizes and binds to promoter sequences on the DNA, thereby initiating transcription.
TFIID, containing the TATA-binding protein (TBP), is crucial for initiating eukaryotic transcription by binding to the TATA box.
Answer: True
TFIID is a key component in eukaryotic transcription initiation. Its TATA-binding protein (TBP) subunit binds to the TATA box in the promoter, serving as an initial recognition step for the assembly of the preinitiation complex.
TFIIH's primary role in transcription is to bind the TATA box, initiating the preinitiation complex.
Answer: False
TFIIH is a general transcription factor involved in eukaryotic transcription initiation, but its primary role is not TATA box binding. TFIID, specifically the TATA-binding protein (TBP) within it, binds the TATA box. TFIIH's key function is promoter escape, facilitated by its helicase and kinase activities, which phosphorylate the C-terminal domain (CTD) of RNA polymerase II.
Which of the following is a key component of the eukaryotic transcription preinitiation complex?
Answer: TFIID
TFIID is a crucial general transcription factor in the eukaryotic preinitiation complex (PIC), responsible for recognizing promoter elements like the TATA box via its TBP subunit.
What characterizes abortive initiation in transcription?
Answer: Repeated synthesis of short, truncated RNA transcripts without promoter escape.
Abortive initiation is a phenomenon where RNA polymerase repeatedly synthesizes short, truncated RNA transcripts without successfully escaping the promoter. This process continues until a transcript of sufficient length is produced, allowing promoter escape.
The mechanism known as 'DNA scrunching' is thought to contribute to which step of transcription?
Answer: Promoter Escape
DNA scrunching is a proposed mechanism where the DNA is unwound and distorted within the RNA polymerase during transcription initiation. This process is thought to provide the necessary energy to break the interactions between the RNA polymerase and the promoter, facilitating promoter escape.
What is the function of the sigma factor in bacterial transcription?
Answer: To recognize and bind to promoter sequences.
In bacteria, the sigma factor binds to RNA polymerase, forming a holoenzyme that specifically recognizes and binds to promoter sequences on the DNA, thereby initiating transcription.
What is the role of TFIIH in eukaryotic transcription initiation?
Answer: Phosphorylating the CTD of RNA polymerase II to aid promoter escape.
TFIIH is a general transcription factor involved in eukaryotic transcription initiation. Its key function is promoter escape, facilitated by its helicase and kinase activities, which phosphorylate the C-terminal domain (CTD) of RNA polymerase II.
In archaea and eukaryotes, what generally replaces the function of the bacterial sigma factor in transcription initiation?
Answer: Multiple general transcription factors
In archaea and eukaryotes, multiple general transcription factors (GTFs) perform the role that sigma factors do in bacteria. These GTFs assemble with RNA polymerase to form the preinitiation complex.
What is the 'transcription bubble'?
Answer: A region of unwound, single-stranded DNA during initiation.
The transcription bubble is a region of unwound, single-stranded DNA formed during transcription initiation. It is where RNA polymerase selects the transcription start site and begins synthesizing the RNA transcript by binding complementary nucleotides.
The TATA-binding protein (TBP) is a key subunit of TFIIB in eukaryotes.
Answer: False
The TATA-binding protein (TBP) is a subunit of TFIID, not TFIIB. TFIID is a crucial general transcription factor in the eukaryotic preinitiation complex (PIC), responsible for recognizing promoter elements like the TATA box via its TBP subunit.
TFIIH is responsible for the initial binding to the TATA box in eukaryotic transcription.
Answer: False
TFIIH is a general transcription factor involved in eukaryotic transcription initiation, but its primary role is not TATA box binding. TFIID, specifically the TATA-binding protein (TBP) within it, binds the TATA box. TFIIH's key function is promoter escape, facilitated by its helicase and kinase activities.
RNA polymerase synthesizes RNA by reading the DNA template strand in the 5' to 3' direction.
Answer: False
RNA polymerase synthesizes RNA by reading the DNA template strand in the 3' to 5' direction. This antiparallel reading allows for the synthesis of the RNA molecule in the 5' to 3' direction.
Nucleosomes do not impede the process of transcription elongation in eukaryotic cells.
Answer: False
In eukaryotes, nucleosomes, which are structures of DNA wrapped around histone proteins, act as significant barriers to the progression of RNA polymerase during transcription elongation. Specialized factors are required to navigate these structures.
Rho-independent termination in bacteria relies on the Rho protein binding to the RNA transcript.
Answer: False
Rho-independent termination in bacteria involves a specific RNA sequence forming a hairpin loop followed by a run of uracils, which causes RNA polymerase to pause and dissociate. Rho-dependent termination, conversely, requires the Rho protein to bind the RNA and destabilize the DNA-RNA hybrid.
Polyadenylation is the process of adding a tail of adenine nucleotides, often associated with transcription termination in eukaryotes.
Answer: True
In eukaryotes, transcription termination is often coupled with the cleavage of the RNA transcript and the subsequent addition of a tail of adenine nucleotides, a process known as polyadenylation.
The C-terminal domain (CTD) of RNA polymerase is involved in scaffolding proteins for post-transcriptional RNA modifications like splicing and capping.
Answer: True
The C-terminal domain (CTD) of RNA polymerase acts as a scaffold, recruiting factors necessary for various post-transcriptional RNA modifications, including 5' capping, splicing, and 3' polyadenylation, as the RNA transcript is synthesized.
Rho-dependent termination requires a specific sequence in the DNA that causes RNA polymerase to pause.
Answer: False
Rho-dependent termination in bacteria involves the Rho protein binding to the RNA transcript and moving towards the polymerase. While specific sequences can influence pausing, the primary mechanism involves Rho destabilizing the DNA-RNA hybrid. Rho-independent termination relies on RNA secondary structures and a run of uracils.
How does RNA polymerase elongate the RNA transcript?
Answer: By reading the DNA template 3' to 5' and synthesizing RNA 5' to 3'.
During elongation, RNA polymerase moves along the DNA template strand (3' to 5'), using base pairing rules to synthesize a complementary RNA strand in the 5' to 3' direction. This process continues until transcription termination signals are encountered.
What poses a significant barrier to transcription elongation in eukaryotes?
Answer: Nucleosomes
In eukaryotes, nucleosomes, which are structures of DNA wrapped around histone proteins, act as significant barriers to the progression of RNA polymerase during transcription elongation. Specialized factors are required to navigate these structures.
Which mechanism of bacterial transcription termination involves a hairpin loop structure in the RNA followed by a run of uracils?
Answer: Rho-independent termination
Rho-independent termination in bacteria involves a specific RNA sequence forming a hairpin loop followed by a run of uracils, which causes RNA polymerase to pause and dissociate. Rho-dependent termination, conversely, requires the Rho protein to bind the RNA and destabilize the DNA-RNA hybrid.
What is polyadenylation in the context of eukaryotic transcription?
Answer: The addition of a tail of adenine nucleotides to the RNA transcript, often linked to termination.
In eukaryotes, transcription termination is often coupled with the cleavage of the RNA transcript and the subsequent addition of a tail of adenine nucleotides, a process known as polyadenylation.
What is the function of the C-terminal domain (CTD) of RNA polymerase?
Answer: To act as a scaffold for proteins involved in RNA modifications.
The C-terminal domain (CTD) of RNA polymerase acts as a scaffold, recruiting factors necessary for various post-transcriptional RNA modifications, including 5' capping, splicing, and 3' polyadenylation, as the RNA transcript is synthesized.
What role does the Rho protein play in bacterial transcription?
Answer: Stabilizing the DNA-RNA hybrid during termination (Rho-dependent).
Rho-dependent termination in bacteria involves the Rho protein binding to the RNA transcript and moving towards the polymerase. Rho then destabilizes the DNA-RNA hybrid, leading to the release of the RNA transcript and polymerase.
Transcription reduces a cell's susceptibility to DNA damage by stabilizing single-stranded DNA.
Answer: False
Transcription can increase a cell's susceptibility to DNA damage. The process involves transiently exposing single-stranded DNA regions, which are inherently more vulnerable to damage than double-stranded DNA. Additionally, the activity of transcription-related enzymes can sometimes introduce DNA breaks.
During elongation, RNA polymerase synthesizes RNA by reading the DNA template from 5' to 3'.
Answer: False
RNA polymerase synthesizes RNA by reading the DNA template strand in the 3' to 5' direction. This antiparallel reading allows for the synthesis of the RNA molecule in the 5' to 3' direction.
What role does the Rho protein play in bacterial transcription?
Answer: Stabilizing the DNA-RNA hybrid during termination (Rho-dependent).
Rho-dependent termination in bacteria involves the Rho protein binding to the RNA transcript and moving towards the polymerase. Rho then destabilizes the DNA-RNA hybrid, leading to the release of the RNA transcript and polymerase.
Enhancers are cis-regulatory elements that can be located far upstream or downstream from the gene they regulate.
Answer: True
Enhancers are key gene-regulatory elements that control cell-type-specific gene expression. They can be located near the transcription start site or at distant locations, either upstream or downstream from the gene's coding sequence.
The Mediator complex directly binds to enhancers and transmits signals to DNA polymerase.
Answer: False
The Mediator complex serves as a molecular bridge, transmitting regulatory signals from transcription factors bound to enhancers and other distal regulatory elements to RNA polymerase II at the promoter, thereby modulating transcription initiation.
Enhancer RNAs (eRNAs) are transcribed from enhancer regions and are thought to help regulate target gene transcription.
Answer: True
Enhancer RNAs (eRNAs) are RNA molecules transcribed from enhancer regions of the genome. Active enhancers typically transcribe eRNAs from both DNA strands, and these molecules are thought to play a role in regulating the transcription of target genes.
CpG island methylation in a gene's promoter typically enhances gene transcription.
Answer: False
CpG island methylation within a gene's promoter region is generally associated with transcriptional repression or silencing, rather than enhancement. This epigenetic modification recruits proteins that lead to a more condensed chromatin structure, hindering transcription.
CpG islands are most commonly found in enhancer sequences rather than gene promoters.
Answer: False
CpG islands, which are regions rich in CpG dinucleotides, are frequently found at the promoters of genes. While about 60% of promoter sequences have CpG islands, only about 6% of enhancer sequences do, suggesting a primary role for CpG islands in promoter regulation.
Methyl-CpG-binding domain (MBD) proteins bind to unmethylated CpG sites and promote transcription.
Answer: False
Methyl-CpG-binding domain (MBD) proteins specifically bind to methylated CpG sites. Upon binding, they recruit corepressor complexes and chromatin remodeling enzymes, leading to transcriptional repression, not promotion.
The human genome is estimated to encode over 5,000 different transcription factors.
Answer: False
It is estimated that the human genome encodes approximately 1,400 different transcription factors, which are proteins that bind to specific DNA sequences to regulate gene expression.
Approximately 94% of transcription factor binding sites for signal-responsive genes are located in promoters.
Answer: False
For signal-responsive genes, approximately 94% of transcription factor binding sites (TFBSs) are located in enhancers, with only about 6% found in promoters. This highlights the critical role of enhancers in regulating gene expression in response to cellular signals.
EGR1 is a transcription factor that can facilitate the demethylation of CpG islands upon neuronal activation.
Answer: True
EGR1 is a transcription factor that is upregulated upon neuronal activation. It recruits TET1 enzymes to EGR1 binding sites in promoters, facilitating the demethylation of CpG islands, which in turn allows transcription of target genes to commence.
In cancer, DNA methylation of promoter CpG islands often leads to the activation of tumor suppressor genes.
Answer: False
In the context of cancer, DNA methylation of promoter CpG islands frequently results in the transcriptional silencing, or inactivation, of tumor suppressor genes. This epigenetic dysregulation contributes significantly to oncogenesis.
Transcriptionally inhibiting the BRCA1 gene is a common occurrence in normal breast cells.
Answer: False
While transcriptional inhibition of genes like BRCA1 can occur and is relevant in certain disease contexts such as breast cancer, it is not described as a common occurrence in normal breast cells. The source indicates that specific genes can be repressed in breast cancer.
How does DNA methylation of promoter CpG islands contribute to cancer progression?
Answer: By transcriptionally silencing tumor suppressor genes.
In the context of cancer, DNA methylation of promoter CpG islands frequently results in the transcriptional silencing, or inactivation, of tumor suppressor genes. This epigenetic dysregulation contributes significantly to oncogenesis.
Which of the following is a mechanism for transcriptionally silencing genes, as mentioned in the context of cancer?
Answer: CpG island methylation
CpG island methylation within a gene's promoter region is generally associated with transcriptional repression or silencing, rather than enhancement. This epigenetic modification recruits proteins that lead to a more condensed chromatin structure, hindering transcription.
Cis-regulatory elements that control cell-type-specific gene expression and often loop DNA to interact with promoters are called:
Answer: Enhancers
Enhancers are key gene-regulatory elements that control cell-type-specific gene expression. They often work by looping DNA to physically interact with gene promoters, and their activity is heavily influenced by specific transcription factors that bind to them.
RNA molecules transcribed from enhancer regions are known as:
Answer: eRNAs
Enhancer RNAs (eRNAs) are RNA molecules transcribed from enhancer regions of the genome. Active enhancers typically transcribe eRNAs from both DNA strands, and these molecules are thought to play a role in regulating the transcription of target genes.
Which epigenetic mechanism can lead to the inhibition or silencing of gene transcription by altering chromatin structure?
Answer: CpG island methylation
CpG island methylation within a gene's promoter region is generally associated with transcriptional repression or silencing, rather than enhancement. This epigenetic modification recruits proteins that lead to a more condensed chromatin structure, hindering transcription.
Where are CpG islands most frequently located in relation to gene regulation, according to the source?
Answer: Primarily at the promoters of genes.
CpG islands, which are regions rich in CpG dinucleotides, are frequently found at the promoters of genes. While about 60% of promoter sequences have CpG islands, only about 6% of enhancer sequences do, suggesting a primary role for CpG islands in promoter regulation.
MBD proteins are involved in transcription regulation by binding to methylated CpG sites and:
Answer: Recruiting chromatin remodeling complexes to create a repressive environment.
Methyl-CpG-binding domain (MBD) proteins specifically bind to methylated CpG sites. Upon binding, they recruit corepressor complexes and chromatin remodeling enzymes, leading to transcriptional repression, not promotion.
Approximately how many transcription factors are estimated to be encoded by the human genome?
Answer: Around 1,400
It is estimated that the human genome encodes approximately 1,400 different transcription factors, which are proteins that bind to specific DNA sequences to regulate gene expression.
For signal-responsive genes, where are the vast majority of transcription factor binding sites (TFBSs) located?
Answer: In enhancers (approx. 94%)
For signal-responsive genes, approximately 94% of transcription factor binding sites (TFBSs) are located in enhancers, with only about 6% found in promoters. This highlights the critical role of enhancers in regulating gene expression in response to cellular signals.
What specific action does the transcription factor EGR1 perform upon neuronal activation, according to the source?
Answer: It recruits TET1 enzymes to demethylate CpG islands.
EGR1 is a transcription factor that is upregulated upon neuronal activation. It recruits TET1 enzymes to EGR1 binding sites in promoters, facilitating the demethylation of CpG islands, which in turn allows transcription of target genes to commence.
Transcription factors bind to promoter-proximal elements and enhancers to regulate gene expression.
Answer: True
Transcription factors are proteins that bind to specific DNA sequences, such as promoter-proximal elements and enhancers, to modulate the rate of transcription of target genes.
Enhancer RNAs (eRNAs) are transcribed from enhancer regions and are typically non-coding.
Answer: True
Enhancer RNAs (eRNAs) are RNA molecules transcribed from enhancer regions of the genome. Active enhancers typically transcribe eRNAs from both DNA strands, and these molecules are thought to play a role in regulating the transcription of target genes.
Cis-regulatory elements that control cell-type-specific gene expression and often loop DNA to interact with promoters are called:
Answer: Enhancers
Enhancers are key gene-regulatory elements that control cell-type-specific gene expression. They often work by looping DNA to physically interact with gene promoters, and their activity is heavily influenced by specific transcription factors that bind to them.
RNA molecules transcribed from enhancer regions are known as:
Answer: eRNAs
Enhancer RNAs (eRNAs) are RNA molecules transcribed from enhancer regions of the genome. Active enhancers typically transcribe eRNAs from both DNA strands, and these molecules are thought to play a role in regulating the transcription of target genes.
Which epigenetic mechanism can lead to the inhibition or silencing of gene transcription by altering chromatin structure?
Answer: CpG island methylation
CpG island methylation within a gene's promoter region is generally associated with transcriptional repression or silencing, rather than enhancement. This epigenetic modification recruits proteins that lead to a more condensed chromatin structure, hindering transcription.
Where are CpG islands most frequently located in relation to gene regulation, according to the source?
Answer: Primarily at the promoters of genes.
CpG islands, which are regions rich in CpG dinucleotides, are frequently found at the promoters of genes. While about 60% of promoter sequences have CpG islands, only about 6% of enhancer sequences do, suggesting a primary role for CpG islands in promoter regulation.
MBD proteins are involved in transcription regulation by binding to methylated CpG sites and:
Answer: Recruiting chromatin remodeling complexes to create a repressive environment.
Methyl-CpG-binding domain (MBD) proteins specifically bind to methylated CpG sites. Upon binding, they recruit corepressor complexes and chromatin remodeling enzymes, leading to transcriptional repression, not promotion.
Approximately how many transcription factors are estimated to be encoded by the human genome?
Answer: Around 1,400
It is estimated that the human genome encodes approximately 1,400 different transcription factors, which are proteins that bind to specific DNA sequences to regulate gene expression.
For signal-responsive genes, where are the vast majority of transcription factor binding sites (TFBSs) located?
Answer: In enhancers (approx. 94%)
For signal-responsive genes, approximately 94% of transcription factor binding sites (TFBSs) are located in enhancers, with only about 6% found in promoters. This highlights the critical role of enhancers in regulating gene expression in response to cellular signals.
What specific action does the transcription factor EGR1 perform upon neuronal activation, according to the source?
Answer: It recruits TET1 enzymes to demethylate CpG islands.
EGR1 is a transcription factor that is upregulated upon neuronal activation. It recruits TET1 enzymes to EGR1 binding sites in promoters, facilitating the demethylation of CpG islands, which in turn allows transcription of target genes to commence.
Transcription factors bind to promoter-proximal elements and enhancers to regulate gene expression.
Answer: True
Transcription factors are proteins that bind to specific DNA sequences, such as promoter-proximal elements and enhancers, to modulate the rate of transcription of target genes.
Enhancer RNAs (eRNAs) are transcribed from enhancer regions and are typically non-coding.
Answer: True
Enhancer RNAs (eRNAs) are RNA molecules transcribed from enhancer regions of the genome. Active enhancers typically transcribe eRNAs from both DNA strands, and these molecules are thought to play a role in regulating the transcription of target genes.
Which of the following is a mechanism for transcriptionally silencing genes, as mentioned in the context of cancer?
Answer: CpG island methylation
CpG island methylation within a gene's promoter region is generally associated with transcriptional repression or silencing, rather than enhancement. This epigenetic modification recruits proteins that lead to a more condensed chromatin structure, hindering transcription.
Reverse transcription is the process of synthesizing RNA from a DNA template.
Answer: False
Reverse transcription is the process of synthesizing DNA from an RNA template, a mechanism utilized by retroviruses and certain cellular enzymes like telomerase. The synthesis of RNA from a DNA template is known as transcription.
Telomerase uses reverse transcription to add repetitive sequences to the ends of chromosomes.
Answer: True
Telomerase is an enzyme that performs reverse transcription to synthesize telomeres, which are repetitive DNA sequences, at the ends of linear chromosomes, thereby counteracting the shortening that occurs during DNA replication.
The process of synthesizing DNA from an RNA template is called:
Answer: Reverse Transcription
Reverse transcription is the process of synthesizing DNA from an RNA template, a mechanism utilized by retroviruses and certain cellular enzymes like telomerase.
Which enzyme performs reverse transcription to maintain telomere length?
Answer: Telomerase
Telomerase is an enzyme that performs reverse transcription to synthesize telomeres, which are repetitive DNA sequences, at the ends of linear chromosomes, thereby counteracting the shortening that occurs during DNA replication.
What is the function of telomerase in normal eukaryotic cells?
Answer: To synthesize telomeres, protecting chromosome ends from shortening.
In normal eukaryotic cells, telomerase synthesizes telomeres, which are repetitive DNA sequences, at the ends of linear chromosomes. This process protects the coding DNA from shortening during each round of DNA replication.
In normal eukaryotic cells, telomerase activity leads to the progressive shortening of chromosome ends.
Answer: False
In normal eukaryotic cells, telomerase activity counteracts the progressive shortening of chromosome ends (telomeres) that occurs during DNA replication. Telomerase synthesizes telomeric DNA, thereby maintaining chromosome stability.
What is the function of telomerase in normal eukaryotic cells?
Answer: To synthesize telomeres, protecting chromosome ends from shortening.
In normal eukaryotic cells, telomerase synthesizes telomeres, which are repetitive DNA sequences, at the ends of linear chromosomes. This process protects the coding DNA from shortening during each round of DNA replication.
In bacteria, the Mfd ATPase is involved in removing stalled RNA polymerase and recruiting DNA repair machinery.
Answer: True
The Mfd ATPase in bacteria helps remove stalled RNA polymerase from DNA lesions. It also recruits nucleotide excision repair machinery and is proposed to resolve conflicts between DNA replication and transcription processes.
TTF2 ATPase in eukaryotes helps activate RNA polymerases during mitosis.
Answer: False
In eukaryotes, the TTF2 ATPase helps suppress the activity of RNA polymerases I and II during mitosis. This suppression is important for preventing errors in chromosome segregation.
Severo Ochoa is credited with hypothesizing the existence of mRNA.
Answer: False
François Jacob and Jacques Monod hypothesized the existence of molecules that transfer genetic information for protein synthesis. Severo Ochoa later won a Nobel Prize for developing a method to synthesize RNA in vitro using polynucleotide phosphorylase, which aided in deciphering the genetic code.
Northern blots provide a more comprehensive analysis of the transcriptome than RNA-Seq.
Answer: False
RNA-Seq utilizes next-generation sequencing to analyze entire transcriptomes, allowing for the measurement of RNA abundance and the detection of variations like fusion genes or novel splice sites. Northern blots are a more traditional method for quantifying RNA levels but are less comprehensive than RNA-Seq.
Rifampicin is a transcription inhibitor used to treat fungal infections.
Answer: False
Rifampicin is an antibacterial drug that inhibits bacterial transcription by binding to RNA polymerase. It is used to treat bacterial infections, not fungal infections.
Transcription factories are nuclear sites where transcription units are dispersed and randomly located.
Answer: False
Transcription factories are discrete sites within the cell nucleus where active transcription units are clustered. These sites can be visualized and contain multiple RNA polymerases and associated transcription units, suggesting a spatial organization of gene expression.
The MS2 tagging technique allows for the visualization of transcription as fluorescent spots, revealing it often occurs in bursts.
Answer: True
MS2 tagging involves incorporating specific RNA stem loops into a gene. These loops are then bound by a fluorescent protein, allowing visualization of transcription as a fluorescent spot. This technique has revealed that transcription often occurs in discontinuous bursts.
How does RNA-Seq differ from Northern blots in analyzing RNA?
Answer: RNA-Seq analyzes the entire transcriptome, while Northern blots are typically limited to specific transcripts.
RNA-Seq utilizes next-generation sequencing to analyze entire transcriptomes, allowing for the measurement of RNA abundance and the detection of variations like fusion genes or novel splice sites. Northern blots are a more traditional method for quantifying RNA levels but are less comprehensive than RNA-Seq.
Which drug is mentioned as an inhibitor of bacterial transcription?
Answer: Rifampicin
Rifampicin is an antibacterial drug that inhibits bacterial transcription by binding to RNA polymerase. It is used to treat bacterial infections, not fungal infections.
What is the function of the C-terminal domain (CTD) of RNA polymerase?
Answer: To act as a scaffold for proteins involved in RNA modifications.
The C-terminal domain (CTD) of RNA polymerase acts as a scaffold, recruiting factors necessary for various post-transcriptional RNA modifications, including 5' capping, splicing, and 3' polyadenylation, as the RNA transcript is synthesized.
In bacteria, the Mfd ATPase is involved in removing stalled RNA polymerase and recruiting DNA repair machinery.
Answer: True
The Mfd ATPase in bacteria helps remove stalled RNA polymerase from DNA lesions. It also recruits nucleotide excision repair machinery and is proposed to resolve conflicts between DNA replication and transcription processes.
TTF2 ATPase in eukaryotes helps activate RNA polymerases during mitosis.
Answer: False
In eukaryotes, the TTF2 ATPase helps suppress the activity of RNA polymerases I and II during mitosis. This suppression is important for preventing errors in chromosome segregation.
Severo Ochoa is credited with hypothesizing the existence of mRNA.
Answer: False
François Jacob and Jacques Monod hypothesized the existence of molecules that transfer genetic information for protein synthesis. Severo Ochoa later won a Nobel Prize for developing a method to synthesize RNA in vitro using polynucleotide phosphorylase, which aided in deciphering the genetic code.
Northern blots provide a more comprehensive analysis of the transcriptome than RNA-Seq.
Answer: False
RNA-Seq utilizes next-generation sequencing to analyze entire transcriptomes, allowing for the measurement of RNA abundance and the detection of variations like fusion genes or novel splice sites. Northern blots are a more traditional method for quantifying RNA levels but are less comprehensive than RNA-Seq.
Rifampicin is a transcription inhibitor used to treat fungal infections.
Answer: False
Rifampicin is an antibacterial drug that inhibits bacterial transcription by binding to RNA polymerase. It is used to treat bacterial infections, not fungal infections.
Transcription factories are nuclear sites where transcription units are dispersed and randomly located.
Answer: False
Transcription factories are discrete sites within the cell nucleus where active transcription units are clustered. These sites can be visualized and contain multiple RNA polymerases and associated transcription units, suggesting a spatial organization of gene expression.
The MS2 tagging technique allows for the visualization of transcription as fluorescent spots, revealing it often occurs in bursts.
Answer: True
MS2 tagging involves incorporating specific RNA stem loops into a gene. These loops are then bound by a fluorescent protein, allowing visualization of transcription as a fluorescent spot. This technique has revealed that transcription often occurs in discontinuous bursts.
How does RNA-Seq differ from Northern blots in analyzing RNA?
Answer: RNA-Seq analyzes the entire transcriptome, while Northern blots are typically limited to specific transcripts.
RNA-Seq utilizes next-generation sequencing to analyze entire transcriptomes, allowing for the measurement of RNA abundance and the detection of variations like fusion genes or novel splice sites. Northern blots are a more traditional method for quantifying RNA levels but are less comprehensive than RNA-Seq.
Which drug is mentioned as an inhibitor of bacterial transcription?
Answer: Rifampicin
Rifampicin is an antibacterial drug that inhibits bacterial transcription by binding to RNA polymerase. It is used to treat bacterial infections, not fungal infections.
What is the function of the C-terminal domain (CTD) of RNA polymerase?
Answer: To act as a scaffold for proteins involved in RNA modifications.
The C-terminal domain (CTD) of RNA polymerase acts as a scaffold, recruiting factors necessary for various post-transcriptional RNA modifications, including 5' capping, splicing, and 3' polyadenylation, as the RNA transcript is synthesized.
The 5' triphosphate group on nascent bacterial mRNA is typically modified into a cap in eukaryotes.
Answer: False
The 5' triphosphate group present on the initiating nucleotide of nascent bacterial mRNA is typically modified into a 7-methylguanosine cap in eukaryotes. This capping process is a crucial post-transcriptional modification in eukaryotes, not a direct modification of the triphosphate group itself in bacteria.
The 'External links' section typically contains links to related concepts within the same article or encyclopedia.
Answer: False
The 'External links' section typically provides links to relevant external resources, such as interactive simulations, animations, or related content on other websites, which can offer additional context or learning materials beyond the scope of the article itself.
The MS2 tagging technique has provided evidence that transcription often occurs in what manner?
Answer: In discontinuous bursts.
MS2 tagging involves incorporating specific RNA stem loops into a gene. These loops are then bound by a fluorescent protein, allowing visualization of transcription as a fluorescent spot. This technique has revealed that transcription often occurs in discontinuous bursts.
How does RNA-Seq differ from Northern blots in analyzing RNA?
Answer: RNA-Seq analyzes the entire transcriptome, while Northern blots are typically limited to specific transcripts.
RNA-Seq utilizes next-generation sequencing to analyze entire transcriptomes, allowing for the measurement of RNA abundance and the detection of variations like fusion genes or novel splice sites. Northern blots are a more traditional method for quantifying RNA levels but are less comprehensive than RNA-Seq.