RNA, Transcription, and Translation - GRE
Card 0 of 192
Which of the following is not a phase in translation?
Which of the following is not a phase in translation?
There are four phases in translation: activation, initiation, elongation, and termination. Activation is the process that joins the correct amino acid to the correct tRNA. When the tRNA has an amino acid bound to it, it is "charged." Initiation occurs when the small ribosomal subunit binds the 5' end of mRNA, with the help of initiation factors and other proteins. The structure then recruits a methionine tRNA to the start codon to begin the elongation process. Elongation occurs as charged tRNA molecules transfer their amino acids to the growing polypeptide. Termination results when a stop codon is recognized by release factors and the completed protein is released from the ribosome.
Modification of the transcript occurs after translation has been completed.
There are four phases in translation: activation, initiation, elongation, and termination. Activation is the process that joins the correct amino acid to the correct tRNA. When the tRNA has an amino acid bound to it, it is "charged." Initiation occurs when the small ribosomal subunit binds the 5' end of mRNA, with the help of initiation factors and other proteins. The structure then recruits a methionine tRNA to the start codon to begin the elongation process. Elongation occurs as charged tRNA molecules transfer their amino acids to the growing polypeptide. Termination results when a stop codon is recognized by release factors and the completed protein is released from the ribosome.
Modification of the transcript occurs after translation has been completed.
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Which of the following is not a type of modification that can occur after translation?
Which of the following is not a type of modification that can occur after translation?
Post-translational modifications that may occur after a protein is translated include numerous processes to alter the structure or function of the protein. Trimming modification involves removal of the N- or C - terminal propeptides from zymogens to generate mature proteins. Covalent alterations, including phosphorylation, glycosylation and hydroxylation, are frequently used to modify the structure or energy state of a protein. Proteasomal degradation requires the attachment of ubiquitin to defective proteins to tag them for degradation and digestion. Amino acids from degraded proteins can often be recycled to generate new molecules.
5' capping occurs in the nucleus after transcription and is required for transport of RNA out of the nucleus prior to translation.
Post-translational modifications that may occur after a protein is translated include numerous processes to alter the structure or function of the protein. Trimming modification involves removal of the N- or C - terminal propeptides from zymogens to generate mature proteins. Covalent alterations, including phosphorylation, glycosylation and hydroxylation, are frequently used to modify the structure or energy state of a protein. Proteasomal degradation requires the attachment of ubiquitin to defective proteins to tag them for degradation and digestion. Amino acids from degraded proteins can often be recycled to generate new molecules.
5' capping occurs in the nucleus after transcription and is required for transport of RNA out of the nucleus prior to translation.
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Which of the following ensures that viral gene translation occurs even when host translation is inhibited?
Which of the following ensures that viral gene translation occurs even when host translation is inhibited?
Viruses utilize IRES to allow translation to occur in a 5' cap-independent manner. Translational machinery (ribosomes) are located to the IRES so that translation can occur. 5' guanine cap and 3' poly-A tails are mRNA modifications that are normally necessary to initiate translation, but are cap-dependent. The promoter regulates genes expression on the level of transcription, whereas the 5' UTR regulates translation.
Viruses utilize IRES to allow translation to occur in a 5' cap-independent manner. Translational machinery (ribosomes) are located to the IRES so that translation can occur. 5' guanine cap and 3' poly-A tails are mRNA modifications that are normally necessary to initiate translation, but are cap-dependent. The promoter regulates genes expression on the level of transcription, whereas the 5' UTR regulates translation.
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Most translation occurs by a mRNA cap-dependent mechanism, however, translation can occur by cap-independent initiation. One mechanism by which eukaryotic cells can initiate cap-independent translation is by which of the following approaches?
Most translation occurs by a mRNA cap-dependent mechanism, however, translation can occur by cap-independent initiation. One mechanism by which eukaryotic cells can initiate cap-independent translation is by which of the following approaches?
The correct answer is the internal ribosome entry site. This site is a specific nucleotide sequence that allows for translation initiation in the middle of a mRNA sequence, rather than at the 5' end, and does not require the cap-dependent elF4F initiation complex or the 5'cap. The poly(A)-binding protein complexes with the 3' end of mRNA strands during translation initiation via the cap-dependent mechanism.
The correct answer is the internal ribosome entry site. This site is a specific nucleotide sequence that allows for translation initiation in the middle of a mRNA sequence, rather than at the 5' end, and does not require the cap-dependent elF4F initiation complex or the 5'cap. The poly(A)-binding protein complexes with the 3' end of mRNA strands during translation initiation via the cap-dependent mechanism.
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Which amino acid is the "start" amino acid in a peptide chain?
Which amino acid is the "start" amino acid in a peptide chain?
The correct answer is methionine. The ATG codon triplet in a mRNA strand codes for the start of the peptide, and this first amino acid that is coded by ATG is methionine.
The correct answer is methionine. The ATG codon triplet in a mRNA strand codes for the start of the peptide, and this first amino acid that is coded by ATG is methionine.
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Which of the following codons is the mRNA start codon that initiates translation?
Which of the following codons is the mRNA start codon that initiates translation?
The codon AUG initiates translation in both eukaryotes and prokaryotes. Interaction with this codon by a tRNA molecule allows a methionine residue to enter the ribosome and serve as the starting point for amino acid elongation.
UGA, UAA, and UAG are mRNA stop codons and stop protein synthesis by causing the ribosomal subunits to dissociate and release the polypeptide.
The codon AUG initiates translation in both eukaryotes and prokaryotes. Interaction with this codon by a tRNA molecule allows a methionine residue to enter the ribosome and serve as the starting point for amino acid elongation.
UGA, UAA, and UAG are mRNA stop codons and stop protein synthesis by causing the ribosomal subunits to dissociate and release the polypeptide.
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In eukaryotes, which RNA polymerase makes rRNA?
In eukaryotes, which RNA polymerase makes rRNA?
The RNA polymerases are numbered in the order that their products are used in protein synthesis.
RNA polymerase I makes ribosomal rRNA in eukaryotes.
RNA polymerase II makes messenger mRNA in eukaryotes.
RNA polymerase III makes transfer tRNA in eukaryotes.
The RNA polymerases are numbered in the order that their products are used in protein synthesis.
RNA polymerase I makes ribosomal rRNA in eukaryotes.
RNA polymerase II makes messenger mRNA in eukaryotes.
RNA polymerase III makes transfer tRNA in eukaryotes.
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Which of the following subunits of RNA polymerase is solely required for initiation of transcription?
Which of the following subunits of RNA polymerase is solely required for initiation of transcription?
The sigma factor is solely required for the initiation of transcription. In fact, the sigma subunit will often fall off of the enzyme during the elongation phase of transcription. Binding of the sigma factor is an important signal for transcription to begin.
The other subunits are crucial to the elongation and termination phases.
The sigma factor is solely required for the initiation of transcription. In fact, the sigma subunit will often fall off of the enzyme during the elongation phase of transcription. Binding of the sigma factor is an important signal for transcription to begin.
The other subunits are crucial to the elongation and termination phases.
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Which of the following best describes the key function of helicases during transcription?
Which of the following best describes the key function of helicases during transcription?
Helicases are required for separating two DNA strands so that the rest of transcription can take place. Polymerases work on single strands of DNA, thus the bonds holding the double strands together must be removed.
Helicases are required for separating two DNA strands so that the rest of transcription can take place. Polymerases work on single strands of DNA, thus the bonds holding the double strands together must be removed.
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Transcription factors that are the first to bind DNA in heterochromatin regions, often promote euchromatin formation, and recruit other transcriptional machinery to promote transcription are best known as which of the following?
Transcription factors that are the first to bind DNA in heterochromatin regions, often promote euchromatin formation, and recruit other transcriptional machinery to promote transcription are best known as which of the following?
The correct answer is pioneer factors. Pioneer factors are able to bind DNA in condensed regions and promote euchromatin formation by recruitment of histone demethyltransferases and acteyltransfereses to modify proximal histones. Additionally, these pioneer factors recruit other transcription factors and co-factors to promote transcription. DNA polymerases are involved with DNA replication, not transcription. The RNA holoenzyme is a protein complex consisting of RNA polymerase, transcription factors, and regulator proteins that binds promoters and catalyzes transcription.
The correct answer is pioneer factors. Pioneer factors are able to bind DNA in condensed regions and promote euchromatin formation by recruitment of histone demethyltransferases and acteyltransfereses to modify proximal histones. Additionally, these pioneer factors recruit other transcription factors and co-factors to promote transcription. DNA polymerases are involved with DNA replication, not transcription. The RNA holoenzyme is a protein complex consisting of RNA polymerase, transcription factors, and regulator proteins that binds promoters and catalyzes transcription.
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Before RNA polymerase can initiate transcription, this protein must bind to it, creating the RNA polymerase holoenzyme and allowing for the initiation of transcription.
Before RNA polymerase can initiate transcription, this protein must bind to it, creating the RNA polymerase holoenzyme and allowing for the initiation of transcription.
RNA polymerase cannot initiate transcription by itself. It binds to the promoter but must wait for a sigma factor to bind to it. Now the RNA polymerase holoenzyme can proceed with transcription.
RNA polymerase cannot initiate transcription by itself. It binds to the promoter but must wait for a sigma factor to bind to it. Now the RNA polymerase holoenzyme can proceed with transcription.
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Which of the following is not dependent on the C-terminal domain (CTD) of RNA polymerase II?
Which of the following is not dependent on the C-terminal domain (CTD) of RNA polymerase II?
The correct answer is none of the other answers. Only mRNA transcribed by polymerase II undergo 5' capping, polyadenylation, and splicing. The C-terminal domain of this polymerase serves as a binding site and docking platform for many of the enzymes that initiate these processes. Moreover, experiments in which the CTD is truncated show that mRNA transcripts are not capped, polyadenylated, and spliced.
The correct answer is none of the other answers. Only mRNA transcribed by polymerase II undergo 5' capping, polyadenylation, and splicing. The C-terminal domain of this polymerase serves as a binding site and docking platform for many of the enzymes that initiate these processes. Moreover, experiments in which the CTD is truncated show that mRNA transcripts are not capped, polyadenylated, and spliced.
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Which polymerase is involved in transcribing ribosomal RNA (except 5S rRNA)?
Which polymerase is involved in transcribing ribosomal RNA (except 5S rRNA)?
The correct answer is RNA polymerase I. The sole purpose of RNA polymerase I in eukaryotes is to transcribe ribosomal RNA, with the exception of 5S rRNA, which is transcribed by RNA polymerase III. RNA polymerase III also transcribes tRNAs and other small RNAs. Transcripts of RNA polymerase II are 5' capped, polyadenylated, and spliced to ultimately be translated into functional protein. DNA polymerase IV/V are polymerases involved in DNA replication and repair.
The correct answer is RNA polymerase I. The sole purpose of RNA polymerase I in eukaryotes is to transcribe ribosomal RNA, with the exception of 5S rRNA, which is transcribed by RNA polymerase III. RNA polymerase III also transcribes tRNAs and other small RNAs. Transcripts of RNA polymerase II are 5' capped, polyadenylated, and spliced to ultimately be translated into functional protein. DNA polymerase IV/V are polymerases involved in DNA replication and repair.
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What is the role of the promoter region in the regulation of gene expression?
What is the role of the promoter region in the regulation of gene expression?
The promoter region is the site of a gene where RNA polymerase and other transcription factors bind to DNA, upstream from the gene locus. A mutation in this region commonly results in a decrease in the amount of gene transcribed.
An enhancer region is a stretch of DNA that alters gene expression by binding transcription factors, while a silencer region is a site on the gene where repressor proteins bind. Introns are intervening non-coding segments of DNA that are not expressed in the final protein. Alternative splicing patterns of introns and exons allows for multiple proteins to be generated from a single gene.
The promoter region is the site of a gene where RNA polymerase and other transcription factors bind to DNA, upstream from the gene locus. A mutation in this region commonly results in a decrease in the amount of gene transcribed.
An enhancer region is a stretch of DNA that alters gene expression by binding transcription factors, while a silencer region is a site on the gene where repressor proteins bind. Introns are intervening non-coding segments of DNA that are not expressed in the final protein. Alternative splicing patterns of introns and exons allows for multiple proteins to be generated from a single gene.
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Which of the following are methods for termination of transcription in prokaryotes?
I. Release factor binding
II. Rho-mediated termination
III. Hairpin loop (stem loop) formation
Which of the following are methods for termination of transcription in prokaryotes?
I. Release factor binding
II. Rho-mediated termination
III. Hairpin loop (stem loop) formation
The binding of release factors is a common way to terminate translation, not transcription.
Rho-mediated termination and hairpin loop formation are both common ways to terminate prokaryotic transcription. The formation of the hairpin loop disrupts the transcription machinery and the DNA-RNA interactions, which allows termination of transcription. Rho is a protein that is capable of binding single-stranded RNA and terminating transcription.
The binding of release factors is a common way to terminate translation, not transcription.
Rho-mediated termination and hairpin loop formation are both common ways to terminate prokaryotic transcription. The formation of the hairpin loop disrupts the transcription machinery and the DNA-RNA interactions, which allows termination of transcription. Rho is a protein that is capable of binding single-stranded RNA and terminating transcription.
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What event is indicative of transcription initiation?
What event is indicative of transcription initiation?
During the initiation of transcription, RNA polymerase and a group of transcription factors bind to the promoter for a given gene. This DNA segment signals the RNA polymerase where to begin creating the RNA strand.
During the initiation of transcription, RNA polymerase and a group of transcription factors bind to the promoter for a given gene. This DNA segment signals the RNA polymerase where to begin creating the RNA strand.
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Which of the following best describes distant regulatory sequences that influence gene expression?
Which of the following best describes distant regulatory sequences that influence gene expression?
The correct answer is enhancer. Transcription factors and mediators bind enhancer regions of DNA and influence the transcription of distant genes by chromatin looping to the proximal promoter. Promoters are regulatory sequences, however, they are typically 2 kilobase pairs upstream of the gene for which they influence transcription. Introns and exons make up a gene and are the non-coding and coding regions of the gene, respectively. The transcriptional start site consists of the first few nucleotides that are transcribed into an mRNA sequence from a gene, usually containing the 5' untranslated region (UTR).
The correct answer is enhancer. Transcription factors and mediators bind enhancer regions of DNA and influence the transcription of distant genes by chromatin looping to the proximal promoter. Promoters are regulatory sequences, however, they are typically 2 kilobase pairs upstream of the gene for which they influence transcription. Introns and exons make up a gene and are the non-coding and coding regions of the gene, respectively. The transcriptional start site consists of the first few nucleotides that are transcribed into an mRNA sequence from a gene, usually containing the 5' untranslated region (UTR).
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When does alternative splicing occur?
When does alternative splicing occur?
The correct answer is following pre-mRNA transcription in the nucleus. Pre-mRNA contains introns and exons. Following transcription, splicing and alternative splicing occurs to remove introns and select exons, respectively, by the spliceosome. Following splicing, 3' poly adenylation and 5' capping occur to generate a mature mRNA transcript that will translocate to the cytosol and be translated by ribosomes.
The correct answer is following pre-mRNA transcription in the nucleus. Pre-mRNA contains introns and exons. Following transcription, splicing and alternative splicing occurs to remove introns and select exons, respectively, by the spliceosome. Following splicing, 3' poly adenylation and 5' capping occur to generate a mature mRNA transcript that will translocate to the cytosol and be translated by ribosomes.
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What element(s) do all eukaryotic promoter regions share?
What element(s) do all eukaryotic promoter regions share?
Eukaryotic promoters share basic, highly conserved structure. This area does not evolve quickly because it is extremely important in DNA transcription. These promoters (in most cases) include a basic basal promoter like a TATA box, and enhancers that bind to transcription factors.
Eukaryotic promoters share basic, highly conserved structure. This area does not evolve quickly because it is extremely important in DNA transcription. These promoters (in most cases) include a basic basal promoter like a TATA box, and enhancers that bind to transcription factors.
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During transcription of a eukaryotic cell, what determines the template strand?
During transcription of a eukaryotic cell, what determines the template strand?
The TATA box is found in the promoter region of the template strand. This TATA box serves as a signal for the initiation of translation of DNA into mRNA. The location of the promoter region and it's unique base sequence signals the start of the translation process.
The TATA box is found in the promoter region of the template strand. This TATA box serves as a signal for the initiation of translation of DNA into mRNA. The location of the promoter region and it's unique base sequence signals the start of the translation process.
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