Transcription of the Genetic Code: The Biosynthesis of RNA Flashcards
Which of following statements describes a difference between replication of DNA and transcription of RNA?
a. Nucleoside triphosphates are the precursors for replication, but nucleoside diphosphates are used for
transcription.
b. Both strands of DNA are copied in replication, but usually only one is copied in transcription.
c. Base pairing is used to copy the sequence in replication, but not in transcription.
d. The chain grows from the 5’ to the 3’ end in replication, but 3’ to 5’ in transcription.
e. None of these
b
Which of following statements concerning RNA transcription is false?
a. The DNA strands become separated during synthesis.
b. Synthesis of RNA is as accurate as synthesis of DNA
c. The template strand is read in the 3’ → 5’ direction.
d. All 4 ribonucleotides are required.
e. A primer is required for RNA synthesis
b
Which of following statements concerning RNA transcription is false?
a. The release of pyrophosphate from a nucleoside triphosphate drives the reaction.
b. RNA is synthesized from the 5’ end to the 3’ end.
c. DNA to RNA base pairing includes A to U and G to C.
d. Transcription requires the use of a primer.
e. None of these
d
The enzyme principally responsible for RNA synthesis in Escherichia coli
a. is a multisubunit enzyme
b. consists of a single polypeptide chain
c. requires Mn2+ for activity
d. requires a DNA primer
a
The end of the new mRNA molecule in E. coli. usually terminates in a string of A’s
a. True
b. False
b
Which of the following correctly describes a difference between RNA & DNA polymerases?
a. RNA polymerases usually do not need a template, while DNA polymerases do.
b. DNA polymerases usually require a primer (i.e., they can only continue a strand, not start one), while most RNA polymerases do not.
c. RNA polymerases usually synthesize introns, while DNA polymerases synthesize cistrons.
d. RNA polymerases polymerize 5’ → 3’, while DNA polymerases polymerize 3’ → 5’.
e. None of these
b
How do the core enzyme and the holoenzyme of RNA polymerase differ in E. coli?
a. The holoenzyme includes the sigma (σ) subunit, the core enzyme does not.
b. The core enzyme includes the sigma (σ) subunit, the holoenzyme does not.
c. The holoenzyme transcribes from an RNA template, the core enzyme from a DNA template.
d. The core enzyme transcribes from an RNA template, the holoenzyme from a DNA template.
a
Which of these terms does not describe the DNA strand used to direct RNA synthesis?
a. Template strand
b. Coding strand
c. Antisense strand
d. Negative or “−” strand
e. All these terms describe the DNA strand used to direct RNA synthesis
b
At what point does the sigma (σ) subunit of RNA polymerase released from the core enzyme?
a. Prior to the incorporation of any nucleotides into an RNA strand.
b. After transcription begins and about 10 nucleotides have been added to the RNA chain.
c. Just prior to chain termination.
d. Never; it is an intrinsic part of the core enzyme.
e. After RNA polymerase discovers an inverted repeat
b
RNA synthesis begins at the base in the DNA sequence designated by the following number:
a. +1 (plus one)
b. 0 (zero)
c. −1 (minus one)
d. −10 region (minus ten)
e. It varies between genes.
a
What is the function of the sigma (σ) subunit of RNA polymerase in E. coli?
a. It recognizes promoters where transcription should begin.
b. It contains the active site for synthesis of RNA.
c. It ensures proper processitvity of the polymerase, so it doesn’t stop prematurely.
d. It is involved in chain termination.
e. It scrunches the DNA
a
Which of the following is not a property of the sigma (σ) subunit?
a. It tells the RNA Polymerase where to sit down.
b. It helps point the RNA Polymerase in the proper direction.
c. It causes the RNA Polymerase to bind tightly to the DNA.
d. It stays with the RNA Polymerase throughout synthesis.
d
Which of the following is not part of the core promoter?
a. the transcription start site
b. the Pribnow box (−10 region)
c. the −35 region
d. the UP element
d
The promoter site is
a. the start site for transcription in DNA
b. the binding site for regulatory proteins that stimulate transcription
c. the general region of DNA downstream from the start site
d. the site on DNA at which RNA polymerase binds to initiate transcription
e. None of these
d
Which of the following offers the best description of a Pribnow box?
a. A promoter consensus sequence located at approximately −35.
b. A promoter consensus sequence located at approximately −10.
c. A sequence forming a hairpin loop signaling the termination of transcription.
d. A sequence immediately surrounding the start site of transcription.
b
Initiation of RNA biosynthesis involves
a. recognition of the promoter region by the α subunit of RNA polymerase
b. conversion of the closed-promoter complex to the open-promoter complex
c. binding of one of the α subunits of RNA polymerase to each strand of DNA
d. incorporation of four pyrimidine nucleotides in succession
b
Consensus sequences are
a. sequences that are invariant throughout the DNA.
b. sequences required for transcription to occur
c. sequences that have many bases in common
d. sequences that lie far upstream of the core promoter.
c
What provides the energy for rho-dependent chain termination?
a. ATP hydrolysis distinct from any incorporation into the chain.
b. Nucleotide hydrolysis associated with incorporation into the chain.
c. Torsional stress built into the separating DNA strands.
d. There is no energy requirement
a
Minor differences in the consensus sequence for RNA Polymerase
a. can be exploited to vary the amount of mRNA which is synthesized from that gene.
b. dictate the direction that RNA Polymerase proceeds from the promoter.
c. dictate whether sigma (σ) factor is required.
d. never occur.
e. have no effect on transcription
a
Which of the following best describes the order of events at the promoter?
a. open complex → closed complex → transcription initiation
b. closed complex → open complex → transcription initiation
c. open complex → transcription initiation → closed complex
d. transcription initiation → open complex → closed complex
b
What provides the energy for the conversion from the open complex to chain elongation?
a. ATP hydrolysis distinct from any incorporation into the chain.
b. Nucleotide hydrolysis associated with incorporation into the chain.
c. Torsional stress built into the separating DNA strands.
d. Binding of rho (ρ) factor to the holoenzyme.
e. None of these
c
Chain termination occurs, in vivo, when:
a. RNA Polymerase gets to the end of the DNA.
b. The factor called rho (ρ) binds to the DNA.
c. A hairpin loop forms in the template.
d. Either a hairpin loop forms or rho (ρ) catches up with transcription stalled by a hairpin loop
e. None of these
d
In prokaryotic RNA synthesis
a. the rate of incorporation of nucleotides is constant throughout the elongation process
b. the ρ (rho) protein is always required for termination
c. a unique series of three bases leads to termination
d. inverted-repeat sequences in the DNA being transcribed can lead to termination
d
What is the need for a primer in transcription?
a. It ensures the fidelity of the newly synthesized RNA strand.
b. There is none.
c. RNA polymerases requires a preexisting strand with a nucleotide having a 3’−OH.
d. RNA polymerase requires a preexisting strand with a nucleotide having a 5’−OH.
b