Question 1

Which subunit of E.coli RNA polymerase is responsible for the RNA polymerization reaction?
A)$\alpha$
B)$\beta$
C)$\beta$'
D) $\sigma$
E)$\omega$

Accepted Answer

The β subunit of E. coli RNA polymerase is responsible for the RNA polymerization reaction.

Question 2

Which of the following is the first event in the post-translational processing of an E.coli tRNA?
A)ribonuclease P cleavage to create the proper 5' end of the molecule
B)methylation of guanine residues
C)conversion of some uridine residues to pseudouridine
D)endonuclease cleavage of about 170 bases from the 3' end of the molecule
E)removal of 9 nucleotides from the 3' end by ribonuclease D

Accepted Answer

Endonuclease cleavage of about 170 bases from the 3F1F1F1S1F1F1F10 end of the molecule is the first event in the post-translational processing of an E.coli tRNA. This cleavage generates the mature 3' end of the tRNA.

Question 3

The concept of the operon was proposed based on the ability of E.coli to metabolize the disaccharide ________ only when present in large excess over glucose.
A)sucrose
B)cellobiose
C)galactose
D)lactose
E)maltose

Accepted Answer

The concept of the operon was proposed based on E.coli's ability to metabolize lactose only when present in large excess over glucose. This led to the discovery of the lac operon, which controls the transcription of genes involved in lactose metabolism.

Question 4

In eukaryotic cells,RNA polymerase ____ transcribes most of the ribosomal RNA,RNA polymerase ____ transcribes the major structural genes and RNA polymerase ____ transcribes tRNAs.
A)I;II;III
B)I;III;II
C)II;I;III
D)II;III;I
E)III;II;I

Accepted Answer

RNA polymerase I transcribes most of the ribosomal RNA, RNA polymerase II transcribes the major structural genes, and RNA polymerase III transcribes tRNAs.

Question 5

What is required for conversion from the closed-promoter complex to open-promoter complex?
A)ATP binding
B)ATP hydrolysis
C)GTP binding
D)GTP hydrolysis
E)DNA bending

Accepted Answer

DNA bending is required for conversion from the closed-promoter complex to open-promoter complex. This bending facilitates the separation of the two strands of DNA, enabling the RNA polymerase to access the template strand and initiate transcription. ATP or GTP binding/hydrolysis is not directly involved in this process.

Question 6

The E.coli core polymerase is missing the ____ subunit and binds to DNA with _______ specificity than the holoenzyme.
A) $\sigma$;less
B) $\sigma$;greater
C)$\alpha$;less
D)$\alpha$;greater
E)none of the above

Accepted Answer

The answer of The E.coli core polymerase is missing the...

Question 7

What is the mechanism by which enhancers,despite the fact that they are often several kilobase pairs away from the promoter,activate transcription?
A)DNA unwinding
B)DNA looping
C)chromatin remodeling
D)DNA hairpin formation
E)none of the above

Accepted Answer

Enhancers can activate transcription despite being several kilobase pairs away from the promoter because they can interact with the promoter through DNA looping. The enhancer, bound by transcription factors, can loop over to the promoter and interact with the transcriptional machinery to activate transcription. This allows distant regulatory elements to communicate with the gene's promoter and control its transcription.

Question 8

Rifampicin is known to inhibit RNA synthesis in E.coli.Once the first ten nucleotides have been incorporated,rifampicin does not inhibit RNA synthesis.Which of the following best explains how rifampicin functions?
A)rifampicin binds only to the core enzyme when bound to DNA but can bind to the holoenzyme when not bound to DNA
B)rifampicin can bind to RNA polymerase when the polymerase is not bound to DNA but cannot bind when the polymerase is bound to DNA
C)rifampicin only inhibits when the $\alpha$ subunit is bound to the core enzyme
D)rifampicin is able to bind to the nucleotide binding site at any time
E)none of the above

Accepted Answer

Rifampicin can bind to RNA polymerase when the polymerase is not bound to DNA but cannot bind when the polymerase is bound to DNA. Once the first ten nucleotides have been incorporated, the polymerase is already bound to DNA, making it resistant to inhibition by rifampicin.

Question 9

The E.coli promoter region contains a -10 consensus sequence of _________ on the sense strand.
A)GAGAGA
B)CTCTCT
C)GAGGAG
D)GACGTC
E)TATAAT

Accepted Answer

The -10 consensus sequence of the E. coli promoter region on the sense strand is TATAAT, which is crucial for the binding of RNA polymerase to initiate transcription.

Question 10

Phosphorylation of the Rpb1 subunit of pol II causes what to occur?
A)binding to histone proteins
B)hydrogen bonding with guanine residues near the start of transcription
C)dissociation from the promoter
D)transcription termination
E)none of the above

Accepted Answer

Phosphorylation of the Rpb1 subunit of pol II promotes dissociation of the polymerase from the promoter, allowing for elongation of the transcript. It does not directly affect binding to histones or hydrogen bonding with DNA. It also does not cause transcription termination.

Question 11

In vivo,which of the following transcription initiation factors is required for binding to a TATA box?
A)TFIID
B)TFIIE
C)TFIIF
D)TFIIH
E)TAF

Accepted Answer

TFIID is a transcription initiation factor that recognizes and binds to the TATA box within the promoter region of a gene. TFIIE, TFIIF, and TFIIH are also transcription initiation factors that function in the preinitiation complex, but they are not specifically required for binding to the TATA box. TAFs (TBP-associated factors) are proteins that interact with TFIID to regulate its activity, but they themselves do not directly bind to the TATA box.

Question 12

How does the concentration of ribonucleotide triphosphates play a role in the regulation of initiation?
A)a high concentration of ATP is required to form the open-promoter complex
B)high concentration of both ATP and GTP are required to form the open-promoter complex
C)the single nucleotide binding site of RNA polymerase undergoes a conformational change after the first nucleotide to allow subsequent nucleotides to bind more readily
D)binding of the first nucleotide requires a half-saturating concentration of ~100 $\mu$M while the half-saturating concentration for subsequent nucleotides is only ~10 $\mu$M
E)none of the above

Accepted Answer

Binding of the first nucleotide to RNA polymerase requires a higher concentration of ribonucleotide triphosphates compared to subsequent nucleotides. The half-saturation concentration for the first nucleotide is ~100μM while for subsequent nucleotides it is only ~10μM. This allows for efficient initiation and regulation of transcription by controlling the rate of binding of the first nucleotide.

Question 13

As RNA polymerase moves along the DNA,it creates a single stranded region of about 18 base pairs that is called a ________________.
A)transcription bubble
B)transcription single-stranded region
C)transcription droplet
D)transcription vesicle
E)transcription bead

Accepted Answer

The single stranded region of about 18 base pairs that is created by RNA polymerase as it moves along the DNA is called a transcription bubble. This region is created because the enzyme unwinds the double-stranded DNA as it moves and only reads one strand at a time.

Question 14

Which of the following is the most common promoter element for pol II?
A)CAAT box (GGCCAATCT)
B)GC box (GGGCGG)
C)TRE (GAGGGACGTACCGCA)
D)TATA box (TATAAAA)
E)Octamer (ATTTGCAT)

Accepted Answer

The TATA box (TATAAAA) is the most common promoter element for pol II. It is located approximately 25 nucleotides upstream of the transcription start site and is recognized by the TATA-binding protein (TBP), which is part of the transcription factor complex TFIID. The TATA box helps to position RNA polymerase II correctly for transcription initiation.

Question 15

E.coli cells achieve a great deal of gene regulatory expression through the $\sigma$ subunit of RNA polymerase.Which $\sigma$ subunit is present most often since it promotes the production of most of the proteins required under normal conditions within the cell? A) $\sigma$^N B) $\sigma$^S C) $\sigma$^H D) $\sigma$³⁰ E) $\sigma$⁷⁰

Accepted Answer

The question seems to be incorrectly formatted with symbols and numbers that don't correspond to known subunits of RNA polymerase in E. coli. However, the correct answer choice is likely intended to refer to the sigma factor (σ) that is most commonly associated with the RNA polymerase in E. coli under normal conditions, which is σ^70 (sigma 70). This is the primary sigma factor used during exponential growth to recognize the promoters of genes required for most basic functions.

Question 16

Transcription of the 5S rRNA gene occurs by ________ covering the entire gene so that pol III can ____________.
A)TFIIB;transcribe the gene several times before dissociating
B)TFIIIC;transcribe the gene several times before dissociating
C)TFIIB;transcribe both strands of DNA before dissociating
D)TFIIIC;transcribe both strands of DNA before dissociating
E)none of the above

Accepted Answer

Transcription of the 5S rRNA gene occurs by TFIIIC covering the entire gene so that pol III can transcribe the gene several times before dissociating.

Question 17

Which subunit of E.coli RNA polymerase is responsible for DNA binding?
A)$\alpha$
B)$\beta$
C)$\beta$'
D) $\sigma$
E)$\omega$

Accepted Answer

The answer of Which subunit of E.coli RNA polymerase is...

Question 18

Rapid transcription of ribosomal RNA is thought to occur as a result of what unique feature in the DNA that encodes these genes?
A)high A-T content
B)highly repetitive sequence
C)multiple promoter sites that allow high affinity with RNA polymerase
D)presence of hairpin structures in the DNA
E)absence of nucleosomes

Accepted Answer

The answer of Rapid transcription of ribosomal RNA is thought...

Question 19

During factor-independent termination,RNA polymerase pauses upon encountering a _____________ and is then displaced downstream upon encountering a ___________.
A)TATAAT sequence;G-C rich segment
B)G-C rich segment;TATAAT sequence
C)G-C rich segment;string of 4-8 A residues
D)string of 4-8 A residues;TATAAT sequence
E)string of 4-8 A residues;G-C rich segment

Accepted Answer

During factor-independent termination, RNA polymerase pauses upon encountering a G-C rich segment and is then displaced downstream upon encountering a string of 4-8 A residues. Therefore, choice C is the best answer as it correctly identifies the order of the sequences encountered by RNA polymerase during factor-independent termination.

Question 20

What type of enzyme activity is associated with the termination factor $\rho$ ?
A)topoisomerase
B)endonuclease
C)exonuclease
D)helicase
E)ligase

Accepted Answer

The termination factor F1F1F1S1ρF1F1F10 is associated with helicase activity, which is crucial for unwinding the DNA double helix during replication and transcription processes.

Quiz 27: Information Readout: Transcription and Post-Transcriptional Processing

Which subunit of E.coli RNA polymerase is responsible for the RNA polymerization reaction?

Which of the following is the first event in the post-translational processing of an E.coli tRNA?

The concept of the operon was proposed based on the ability of E.coli to metabolize the disaccharide ________ only when present in large excess over glucose.

In eukaryotic cells,RNA polymerase transcribes most of the ribosomal RNA,RNA polymerase transcribes the major structural genes and RNA polymerase transcribes tRNAs.

What is required for conversion from the closed-promoter complex to open-promoter complex?

The E.coli core polymerase is missing the subunit and binds to DNA with ___ specificity than the holoenzyme.

What is the mechanism by which enhancers,despite the fact that they are often several kilobase pairs away from the promoter,activate transcription?

Rifampicin is known to inhibit RNA synthesis in E.coli.Once the first ten nucleotides have been incorporated,rifampicin does not inhibit RNA synthesis.Which of the following best explains how rifampicin functions?

The E.coli promoter region contains a -10 consensus sequence of _________ on the sense strand.

Phosphorylation of the Rpb1 subunit of pol II causes what to occur?

In vivo,which of the following transcription initiation factors is required for binding to a TATA box?

How does the concentration of ribonucleotide triphosphates play a role in the regulation of initiation?

As RNA polymerase moves along the DNA,it creates a single stranded region of about 18 base pairs that is called a ________________.

Which of the following is the most common promoter element for pol II?

E.coli cells achieve a great deal of gene regulatory expression through the $\sigma$ subunit of RNA polymerase.Which $\sigma$ subunit is present most often since it promotes the production of most of the proteins required under normal conditions within the cell?

Transcription of the 5S rRNA gene occurs by covering the entire gene so that pol III can ____.

Which subunit of E.coli RNA polymerase is responsible for DNA binding?

Rapid transcription of ribosomal RNA is thought to occur as a result of what unique feature in the DNA that encodes these genes?

During factor-independent termination,RNA polymerase pauses upon encountering a ___ and is then displaced downstream upon encountering a _.

What type of enzyme activity is associated with the termination factor $\rho$ ?