Question 1

A cluster of genes coding for tRNAs is often referred to as ______.
A)tDNA
B)transferase
C)rDNA
D)t clusters
E)tDNase

Accepted Answer

A cluster of genes coding for tRNAs is referred to as tDNA (transfer RNA genes).

Question 2

Modifications to the nucleotides of pre-rRNAs are made _________.
A)after translation
B)before transcription
C)after transcription
D)after mitosis
E)before mitosis

Accepted Answer

Modifications to pre-rRNAs, such as methylation and pseudouridylation, are made after transcription and processing of the pre-rRNA molecule but before translation. This ensures that the mature rRNA is functional and able to participate in ribosome assembly and protein synthesis.

Question 3

What percentage of cellular RNA is rRNA?
A)less than 20%
B)more than 80%
C)50-60%
D)approximately 35%

Accepted Answer

The answer of What percentage of cellular RNA is rRNA?
A)less...

Question 4

How would you describe the arrangement of the 5S rRNA genes?
A)tandem array with spacers
B)continuous genes
C)tandem array without spacers
D)4 introns between each protein
E)quartile array with duplex spacers

Accepted Answer

The 5S rRNA genes are typically organized in a tandem array with non-coding spacer DNA sequences between each gene unit. This arrangement facilitates the coordinated transcription of multiple rRNA molecules.

Question 5

The combination of DNA, RNA core enzyme and $\sigma$ factor is called _____.
A)an open complex
B)a transcription unit
C)a translation unit
D)a coding unit
E)a transcriptosome

Accepted Answer

The answer of The combination of DNA, RNA core enzyme...

Question 6

Where is the RNA polymerase II phosphorylated during its activation?
A)on the N-terminal end of the largest RNA polymerase II subunit
B)on the central 20 amino acids of the largest RNA polymerase II subunit
C)on the 3' end of the largest RNA polymerase II subunit
D)on the 5' end of the largest RNA polymerase II subunit
E)in the carboxyl-terminal domain (CTD)of the largest RNA polymerase II subunit

Accepted Answer

RNA polymerase II is phosphorylated in the carboxyl-terminal domain (CTD) of the largest subunit. The CTD contains multiple repeats of the heptapeptide sequence YSPTSPS and phosphorylation of specific serine residues in these repeats plays a critical role in activation of RNA polymerase II.

Question 7

What molecule is TFIIH known to phosphorylate?
A)a G protein
B)RNA polymerase II
C)peptidyltransferase
D)DNA helicase

Accepted Answer

TFIIH is known to phosphorylate RNA polymerase II, which is a crucial step in transcription initiation and elongation. TFIIH is a complex protein that unwinds the DNA double helix and helps recruit RNA polymerase II to the promotor region. Once RNA polymerase II is bound, TFIIH phosphorylates the C-terminal domain of RNA polymerase II, allowing it to transition from initiation to elongation and continue transcribing the gene. TFIIH also has helicase activity and unwinds the DNA to facilitate transcription. Therefore, option B is the correct answer.

Question 8

Which enzyme is responsible for synthesizing hnRNAs?
A)RNA polymerase I
B)RNA polymerase II
C)RNA polymerase III
D)reverse transcriptase
E)general transcription factors

Accepted Answer

hnRNAs are synthesized by RNA polymerase II, which is responsible for transcribing protein-coding genes into pre-mRNA. hnRNAs are then processed and modified to become mature mRNA before they are exported from the nucleus for translation.RNA polymerase I transcribes ribosomal RNA genes, RNA polymerase III transcribes transfer RNA and small nuclear RNA genes, reverse transcriptase synthesizes DNA from an RNA template, and general transcription factors are proteins that are required for RNA polymerase to initiate transcription.

Question 9

The chromosome regions containing most rDNA are gathered in __________.
A)terminators
B)nucleoli
C)nucleosomes
D)ribostores
E)telomeres

Accepted Answer

The nucleoli are the site of ribosomal RNA (rRNA) transcription and ribosome assembly. The chromosome regions containing most rDNA are gathered in nucleoli.

Question 10

What is the name of the RNA-degrading machine that consists of nearly a dozen different exonucleases and is thought to execute some of the enzymatic cleavages that occur during pre-rRNA processing?
A)endosome
B)exosome
C)nucleosome
D)heliosome
E)degradosome

Accepted Answer

The RNA-degrading machine that consists of nearly a dozen different exonucleases and is thought to execute some of the enzymatic cleavages that occur during pre-rRNA processing is called the exosome. The other options - endosome, nucleosome, heliosome, and degradosome - are not involved in RNA degradation or pre-rRNA processing.

Question 11

In mammalian cells employed in pulse-chase experiments, radiolabeled methyl groups appear first in which size RNA molecule that is a precursor to rRNA?
A)65S RNA
B)45S RNA
C)28S RNA
D)18S RNA
E)5.8S RNA

Accepted Answer

The precursor to rRNA is the 45S RNA, which is transcribed from the rDNA. Radiolabeled methyl groups appear first in the 45S RNA during pulse-chase experiments. The 45S RNA is processed into 18S, 5.8S, and 28S rRNA molecules.

Question 12

Why are general transcription factors (GTFs)referred to as "general?"
A)The same transcription factors are required for the accurate initiation of transcription of a diverse array of genes in a wide variety of different organisms.
B)The same transcription factors are required for the accurate initiation of translation of a diverse array of genes in a wide variety of different organisms.
C)The same transcription factors are required for the accurate termination of transcription of a diverse array of genes in a wide variety of different organisms.
D)The same transcription factors are required for the accurate termination of translation of a diverse array of genes in a wide variety of different organisms.

Accepted Answer

General transcription factors (GTFs) are referred to as "general" because the same transcription factors are necessary for the accurate initiation of transcription of a diverse array of genes in a wide variety of different organisms. This means that GTFs are not specific to any particular gene or type of organism, but rather are required for the basic process of transcription in all cells.

Question 13

The promoter for tRNA genes (tDNA)is located ________.
A)at the 3' end of the gene
B)within the coding section of the gene
C)at the 5' end of the gene
D)far downstream of the gene
E)far upstream of the gene

Accepted Answer

The promoter for tRNA genes is located within the coding section of the gene, specifically in the internal control region (ICR), which is part of the transcribed region.

Question 14

Most cellular RNA is in what form?
A)hnRNA
B)snoRNA
C)mRNA
D)rRNA
E)hmRNA

Accepted Answer

Most cellular RNA is in the form of ribosomal RNA (rRNA), which is a key component of ribosomes, the cellular machinery for protein synthesis. rRNA makes up the majority of RNA in cells because ribosomes are abundant and essential for the translation process.

Question 15

Heterogeneous nuclear RNAs (hnRNAs)are _________.
A)tRNA precursors
B)mRNA precursors
C)rRNA precursors
D)snoRNA precursors
E)mature snRNAs

Accepted Answer

Heterogeneous nuclear RNAs (hnRNAs) are precursors to messenger RNA (mRNA). The hnRNAs undergo splicing to remove introns and create a mature mRNA molecule that can be translated into protein.

Question 16

You incubate eukaryotic cells for 30 minutes in [³H]uridine and then immediately kill the cells and extract the RNA. Where does the radiolabel appear after this experiment? A)in larger molecular weight RNAs in the nucleus B)in smaller molecular weight RNAs in the mitochondria C)in smaller molecular weight RNAs in the cytoplasm D)in larger molecular weight RNAs in the mitochondria E)in moderately sized RNAs in the Golgi complex

Accepted Answer

The radiolabeled uridine is incorporated into newly synthesized RNA. In eukaryotic cells, transcription of larger molecular weight RNAs, such as precursor mRNAs and ribosomal RNAs, occurs in the nucleus. These RNAs are then processed and either remain in the nucleus or are exported to the cytoplasm. Given the short incubation time, the label would predominantly be found in larger molecular weight RNAs in the nucleus before significant processing or export occurs.

Question 17

How would you describe the half-lives of rRNAs and tRNAs?
A)days or weeks long
B)minutes long
C)seconds long
D)hours long
E)years long

Accepted Answer

The half-lives of rRNAs and tRNAs are relatively long, often lasting days or weeks, because these molecules are stable components of the cellular machinery involved in protein synthesis.

Question 18

RNA polymerase II promoters are located on the ________ side of each transcription unit.
A)3'
B)5'
C)N-terminal
D)C-terminal

Accepted Answer

RNA polymerase II promoters are located on the 5' side of each transcription unit, which is where transcription begins.

Question 19

Pre-rRNAs have more ___________ than other RNA transcripts.
A)pseudouridine residues and thymidine residues
B)thymidine residues and methylated nucleotides
C)pseudouridine residues and methylated nucleotides
D)pseudouridines and pseudocytosines
E)methylated nucleotides and pseudocytosines

Accepted Answer

Pre-rRNAs have more pseudouridine residues and methylated nucleotides than other RNA transcripts. Pseudouridine is the most common modified nucleotide found in RNA and it is known to stabilize RNA structures. Methylated nucleotides are also common in pre-rRNAs and are important for regulating RNA processing and ribosome biogenesis. Thymidine residues are not typically found in RNA, and pseudocytosines are not a well-characterized RNA modification.

Question 20

A larger S value (Svedberg unit)for an RNA indicates that the RNA __________.
A)migrates more rapidly through a field of force during centrifugation
B)migrates less rapidly through a field of force during centrifugation
C)migrates more rapidly through a field of force during gel filtration
D)migrates more rapidly through a field of force during SDS polyacrylamide gel electrophoresis
E)migrates less rapidly through a field of force during SDS polyacrylamide gel electrophoresis

Accepted Answer

A larger S value indicates that the RNA has a higher sedimentation rate and thus migrates more rapidly during centrifugation.

Quiz 11: Gene Expression: From Transcription to Translation

A cluster of genes coding for tRNAs is often referred to as ______.

Modifications to the nucleotides of pre-rRNAs are made _________.

What percentage of cellular RNA is rRNA?

How would you describe the arrangement of the 5S rRNA genes?

The combination of DNA, RNA core enzyme and $\sigma$ factor is called _____.

Where is the RNA polymerase II phosphorylated during its activation?

What molecule is TFIIH known to phosphorylate?

Which enzyme is responsible for synthesizing hnRNAs?

The chromosome regions containing most rDNA are gathered in __________.

What is the name of the RNA-degrading machine that consists of nearly a dozen different exonucleases and is thought to execute some of the enzymatic cleavages that occur during pre-rRNA processing?

In mammalian cells employed in pulse-chase experiments, radiolabeled methyl groups appear first in which size RNA molecule that is a precursor to rRNA?

Why are general transcription factors (GTFs) referred to as "general?"

The promoter for tRNA genes (tDNA) is located ________.

Most cellular RNA is in what form?

Heterogeneous nuclear RNAs (hnRNAs) are _________.

You incubate eukaryotic cells for 30 minutes in [³H]uridine and then immediately kill the cells and extract the RNA. Where does the radiolabel appear after this experiment?

How would you describe the half-lives of rRNAs and tRNAs?

RNA polymerase II promoters are located on the ________ side of each transcription unit.

Pre-rRNAs have more ___________ than other RNA transcripts.

A larger S value (Svedberg unit) for an RNA indicates that the RNA __________.