Question 1

Rho-dependent termination of transcription makes use of a hexameric protein, which has RNA-DNA helicase activity.

Accepted Answer

Rho-dependent termination of transcription uses a hexameric protein called Rho factor, which has RNA-DNA helicase activity.

Question 2

Eukaryotic transcription normally takes place on a chromatin template at nuclease-accessible sites.

Accepted Answer

Eukaryotic transcription occurs on a chromatin template, but the chromatin needs to be remodeled to make the DNA accessible to the transcription machinery. Nucleosomes and other chromatin-associated proteins can inhibit the access of transcription factors to DNA sequences, and chromatin remodeling complexes are required to move or modify these proteins to create nuclease-accessible sites.

Question 3

Which of the following statements is FALSE?
A) RNA polymerase II is responsible for the transcription of genes encoding protein-coding sequences only.
B) Many promoters recognized by RNA polymerase II contain regulatory elements several kbp upstream of the initiation site.
C) TFIIB has a role in converting a closed-promoter into an open-promoter complex.
D) The C-terminal domain of the largest subunit of RNA pol II undergoes extensive phosphorylation prior to transcription elongation.
E) A multiprotein complex is involved in communication between upstream control elements and proteins bound at the promoter.

Accepted Answer

RNA polymerase II is responsible for the transcription of genes encoding both protein-coding sequences and non-coding RNA genes.

Question 4

In bacteria, mRNA, tRNA and rRNA are all transcribed by the same RNA polymerase.

Accepted Answer

In bacteria, there is only one type of RNA polymerase that transcribes all types of RNA - mRNA, tRNA and rRNA.

Question 5

Most ________ of transcription in prokaryotes is based on a weakened interaction due to ________ base pairing between the template and the transcript as well as a stable stem loop structure in the nascent transcript which eliminates base pairing between the template and transcript upstream of the AU interaction.

Accepted Answer

The answer of Most ________ of transcription in prokaryotes is...

Question 6

In eukaryotes RNA polymerase I transcribes all of the ribosomal RNA components.

Accepted Answer

In eukaryotes, RNA polymerase I transcribes the large ribosomal RNA (rRNA) components (28S, 18S, and 5.8S), but not all rRNA components; RNA polymerase III transcribes the 5S rRNA component.

Question 7

Which of the following is FALSE when comparing DNA pol III and RNA polymerase?
A) There are many more copies of RNA polymerase in the cell.
B) DNA pol III is much more processive.
C) RNA polymerase makes more errors.
D) RNA polymerase has a much slower kcat.
E) RNA polymerase does not need a primer.

Accepted Answer

The answer of Which of the following is FALSE when...

Question 8

All the tRNA genes are transcribed by ________ in eukaryotes.

Accepted Answer

The answer of All the tRNA genes are transcribed by...

Question 9

Which of the following statements about E. coli RNA polymerase is INCORRECT?
A) It has five different subunits.
B) The σ subunit can be dissociated easily from the rest of the enzyme.
C) The σ subunit is responsible for accurate determination of transcription start sites.
D) Without the σ subunit the enzyme has no RNA polymerase activity.
E) The σ subunit has a role in regulation of transcription.

Accepted Answer

While the σ subunit plays an important role in accurate determination of transcription start sites and regulation of transcription, it is not required for RNA polymerase activity. The core enzyme, composed of the other four subunits, is capable of catalyzing RNA synthesis without the σ subunit in vitro.

Question 10

Degradation of bacterial mRNAs occurs:
A) from the 3' end.
B) largely by the activity of non-specific nucleases.
C) from the 5' end.
D) relatively slowly.
E) from both 3' and 5' ends at the same time.

Accepted Answer

Bacterial mRNAs are degraded from the 5' end by endoribonucleases and exonucleases. This process is called 5'-3' exonucleolytic decay.

Answer: E
 In addition to 5'-3' exonucleolytic decay, bacterial mRNAs can also undergo 3'-5' exonucleolytic decay, leading to simultaneous degradation from both ends. This process is mediated by endoribonucleases and exonucleases.

Question 11

After promoter clearance by RNA polymerase II:
A) all associated factors remain bound to the polymerase for elongation.
B) a subset of factors remain at the promoter region.
C) no further elongation factors are acquired by the polymerase.
D) no further chromatin remodeling is required.
E) transcription continues until the polymerase reaches the poly (A) tail.

Accepted Answer

After promoter clearance, a subset of transcription factors, such as the TFIID complex, remain at the promoter region to facilitate subsequent rounds of transcription initiation. However, most elongation factors are recruited to the polymerase during the process of mRNA synthesis.

Answer: C
 Elongation factors, such as the P-TEFb complex, are recruited to the polymerase during the process of mRNA synthesis and are not present at the promoter region.

Answer: D
 Chromatin remodeling may still be required during the elongation phase to facilitate the movement of the polymerase through the nucleosomes.

Answer: E
 Transcription may terminate before the polymerase reaches the poly(A) tail, depending on the presence of termination signals and other factors.

Question 12

High levels of histone ________ correlate with high levels of transcriptional activity.

Accepted Answer

The answer of High levels of histone ________ correlate with...

Question 13

RNA polymerase transcribes all DNA sequences at an equal rate.

Accepted Answer

RNA polymerase does not transcribe all DNA sequences at an equal rate. The rate of transcription can be influenced by various factors such as the presence of regulatory elements, chromatin structure, and the availability of transcription factors. Additionally, some genes may have faster or slower transcription rates based on their importance or the need for their protein products at a certain time.

Question 14

In eukaryotes a set of ________ function in a comparable manner to the σ subunit of E. coli RNA polymerase.

Accepted Answer

The answer of In eukaryotes a set of ________ function...

Question 15

Alignment of conserved sequences in promoters recognized by E. coli RNA polymerase revealed two ________ sequences upstream of the transcribed region, which are separated by similar lengths of DNA.

Accepted Answer

The answer of Alignment of conserved sequences in promoters recognized...

Question 16

In bacteria post-transcriptional processing of pre-rRNA species can yield mature tRNAs.

Accepted Answer

Post-transcriptional processing in bacteria can yield mature tRNAs, as well as other RNA species such as rRNA and mRNA. This includes modifications such as cleavage, trimming, splicing, and base modifications that are necessary for their proper function.

Question 17

Which of the following types of post-transcriptional processing does NOT occur for bacterial tRNAs?
A) Exonuclease cleavage
B) Endonuclease cleavage
C) Non-template directed addition of bases
D) Methylation of bases
E) Addition of a phosphate group to the 5' end

Accepted Answer

Bacterial tRNAs do not undergo addition of a phosphate group to the 5' end. This is a modification that occurs in eukaryotic tRNAs to create the mature 5' end. Bacterial tRNAs do undergo exonuclease and endonuclease cleavage, non-template directed addition of bases, and methylation of bases.

Question 18

In eukaryotes genes encoding enzymes for metabolic pathways often exist as operons of several genes with a single regulatory region to provide coordinate regulation of all genes required for the pathway.

Accepted Answer

In eukaryotes, genes encoding enzymes for metabolic pathways are not typically organized into operons. Instead, they are often scattered throughout the genome, with each gene having its own regulatory region. There are some exceptions to this rule, such as in fungi and some plant species, where operons have been identified for certain metabolic pathways. However, this is not a common feature of eukaryotic gene regulation.

Question 19

Which of the following is NOT correct when considering the initiation of transcription in E. coli?
A) The σ subunit of RNA polymerase makes strong contacts with the -10 region of promoters.
B) Only the -10 region of the promoter is required.
C) DNA melting near the transcription start site is essential for promoter recognition.
D) The phosphodiester bonds that are formed are not stable until about 10 nucleotides have been incorporated.
E) The RNA polymerase contacts about 50 bp of DNA.

Accepted Answer

Both the -10 and -35 regions of promoters are required for efficient transcription initiation in E. coli. The σ subunit of RNA polymerase makes strong contacts with both regions, and DNA melting near the transcription start site is also essential for promoter recognition. The phosphodiester bonds formed during transcription are unstable until about 10 nucleotides have been incorporated, as stated in choice D. Choice E is also correct, as RNA polymerase contacts about 50 bp of DNA during transcription initiation. Therefore, the only incorrect statement is choice B, which suggests that only the -10 region is required.

Question 20

The different sensitivities to the toxin ________ revealed that eukaryotes have three distinct RNA polymerases for synthesis of mRNA, rRNA and small RNAs including tRNA and the 5S species of rRNA.

Accepted Answer

The answer of The different sensitivities to the toxin ________...

Quiz 24: Transcription and Post-Transcriptional Processing

Rho-dependent termination of transcription makes use of a hexameric protein, which has RNA-DNA helicase activity.

Eukaryotic transcription normally takes place on a chromatin template at nuclease-accessible sites.

Which of the following statements is FALSE?

In bacteria, mRNA, tRNA and rRNA are all transcribed by the same RNA polymerase.

Most of transcription in prokaryotes is based on a weakened interaction due to base pairing between the template and the transcript as well as a stable stem loop structure in the nascent transcript which eliminates base pairing between the template and transcript upstream of the AU interaction.

In eukaryotes RNA polymerase I transcribes all of the ribosomal RNA components.

Which of the following is FALSE when comparing DNA pol III and RNA polymerase?

All the tRNA genes are transcribed by ________ in eukaryotes.

Which of the following statements about E. coli RNA polymerase is INCORRECT?

Degradation of bacterial mRNAs occurs:

After promoter clearance by RNA polymerase II: