Question 1

The prokaryotic cells most commonly used to study transcription and translation are from
A) E. coli.
B) B. subtilis.
C) S. cerevisiae.
D) D. discoideum.

Accepted Answer

E. coli is one of the most commonly used prokaryotic cells for studying transcription and translation due to its fast growth rate, well-characterized genetics, and ease of manipulation.

Question 2

RNA polymerase differs from DNA polymerase in that it
A) synthesizes new strands of RNA in a 3ʹ to 5ʹ direction.
B) is a monomeric protein.
C) can synthesize a complementary strand without the two strands of DNA being separated.
D) does not require a primer to initiate synthesis of RNA.

Accepted Answer

RNA polymerase does not require a primer to initiate synthesis of RNA, unlike DNA polymerase which needs a primer to add nucleotides to the 3ʹ end of an existing strand.

Question 3

The DNA sequence to which an RNA polymerase binds to initiate transcription of a gene is called a(n)
A) enhancer.
B) promoter.
C) polymerase-binding element.
D) origin of transcription.

Accepted Answer

The DNA sequence to which an RNA polymerase binds to initiate transcription of a gene is called a promoter. The other options (enhancer, polymerase-binding element, origin of transcription) do not accurately describe this sequence.

Question 4

The regions of the DNA where RNA polymerase binds can be identified by
A) restriction mapping.
B) PCR.
C) inhibited transcription following mutagenesis in the -35 and -10 promoter regions.
D) polymerase mapping.

Accepted Answer

Mutagenesis in the -35 and -10 promoter regions would inhibit transcription, indicating that these regions are necessary for RNA polymerase binding. Restriction mapping, PCR, and polymerase mapping do not specifically identify regions where RNA polymerase binds.

Question 5

The role of the sigma ($\sigma$) factor in prokaryote transcription is to
A) unwind the DNA during transcription.
B) direct RNA polymerases to bind to different promoter regions.
C) recognize the transcription initiation site.
D) terminate transcription.

Accepted Answer

The sigma factor is a protein needed for the initiation of transcription in prokaryotes. It directs RNA polymerase to specific promoter regions on the DNA, allowing the enzyme to initiate transcription at the correct site.

Question 6

Transcription of a bacterial gene is initiated
A) with RNA polymerase in the closed-promoter complex.
B) after release of the sigma ($\sigma$) factor.
C) with RNA polymerase in the open-promoter complex.
D) Both b and c

Accepted Answer

Transcription of a bacterial gene is initiated with RNA polymerase in the open-promoter complex, where the DNA helix is unwound and the template strand is available for base pairing with incoming ribonucleotides. The closed-promoter complex is formed when RNA polymerase binds to the promoter region of the DNA but has not yet opened the helix, while release of the sigma factor occurs after initiation and is not a part of the initiation process. Therefore, choices A and B are incorrect. Choice D is incorrect because it includes choice B, which is incorrect.

Question 7

The sigma ($\sigma$) subunit of bacterial RNA polymerase remains associated for the addition of _______ during transcription.
A) the first ten nucleotides
B) the first half of the nucleotides
C) all of the nucleotides
D) the last ten nucleotides

Accepted Answer

The sigma (F1F1F1S1F1F1F10) subunit of bacterial RNA polymerase remains associated for the addition of the first ten nucleotides during transcription. This allows for proper positioning and initiation of transcription at the promoter region. Once the RNA strand reaches a length of about 10 nucleotides, the sigma factor dissociates and transcription continues with the core enzyme.

Question 8

Transcription is _______-dependent _______ synthesis.
A) DNA; DNA
B) DNA; RNA
C) RNA; DNA
D) RNA; protein

Accepted Answer

Transcription is the process of synthesizing a RNA molecule from a DNA template. Therefore, it is DNA-dependent RNA synthesis.

Question 9

Termination of transcription in E. coli is signaled by
A) formation of a stem-loop structure in the RNA.
B) binding of Rho protein to the end of the mRNA.
C) binding of a sigma ($\sigma$) factor to the end of the mRNA.
D) an inverted GC-rich sequence followed by seven A residues.

Accepted Answer

An inverted GC-rich sequence followed by seven A residues is the termination signal for transcription in E. coli.

Question 10

Eukaryotic RNA polymerase I genes code for
A) mRNAs.
B) tRNAs.
C) small nuclear RNAs and small cytoplasmic RNAs.
D) ribosomal RNAs.

Accepted Answer

Eukaryotic RNA polymerase I genes code for ribosomal RNAs (rRNAs). These rRNAs are essential for the assembly of ribosomes, which are responsible for protein synthesis in the cell.

Question 11

Mitochondrial genes are transcribed by
A) RNA polymerase I.
B) RNA polymerase II.
C) RNA polymerase III.
D) a separate mitochondrial RNA polymerase.

Accepted Answer

Mitochondrial genes are transcribed by a separate mitochondrial RNA polymerase, which is distinct from the nuclear RNA polymerases I, II, and III.

Question 12

The large multi-subunit complex that links the general transcription factors to the gene-specific transcription factors is called
A) the transcription complex.
B) Mediator.
C) the operator.
D) TBP.

Accepted Answer

The Mediator is a large multi-subunit complex that links the general transcription factors, including TBP, to the gene-specific transcription factors. It plays a crucial role in regulating transcription initiation and the interaction between the transcriptional machinery and chromatin. The operator is a DNA sequence to which a specific repressor protein can bind, while TBP (TATA-binding protein) is one of the general transcription factors that directly binds to the TATA box element in the core promoter of genes.

Question 13

A major difference between eukaryotic and prokaryotic RNA polymerases is that eukaryotic polymerases
A) use a set of transcription factors to bind to and initiate transcription.
B) use sigma ($\sigma$) factors to initiate transcription.
C) start from promoters.
D) start from origins of replication.

Accepted Answer

Eukaryotic RNA polymerases require a set of transcription factors (TFIIA, TFIIB, TFIID, TFIIE, TFIIF, and TFIIH) to bind to specific DNA sequences called promoters and initiate transcription. Prokaryotic RNA polymerases do not require transcription factors but instead use sigma factors to bind to specific DNA sequences and initiate transcription.

Question 14

The TATA box is similar to the _______ in E. coli.
A) -35 promoter sequence
B) -10 promoter sequence
C) +1 transcription start site
D) None of the above

Accepted Answer

The TATA box in eukaryotic promoters is similar to the -10 promoter sequence in E. coli, as both regions are recognized by RNA polymerase and are involved in the initiation of transcription. The -35 promoter sequence in E. coli is also recognized by RNA polymerase, but it serves a slightly different function than the TATA box in eukaryotic promoters. The +1 transcription start site is not similar to the TATA box in any way. Therefore, the best choice is B, the -10 promoter sequence.

Question 15

The first step in the formation of a transcription complex for mRNA transcription is the binding of _______ to the TATA box.
A) TFIA
B) TFIIA
C) TFIIIA
D) TFIID

Accepted Answer

TFIID is the general transcription factor that binds to the TATA box in eukaryotic cells to initiate transcription.

Question 16

Release of RNA polymerase II to initiate transcription appears to be the direct result of the
A) binding of TAFs to the polymerase.
B) unwinding of the DNA by helicases.
C) phosphorylation of RNA polymerase by a protein kinase.
D) removal of the nucleosome occupying the promoter site.

Accepted Answer

Phosphorylation of RNA polymerase II by a protein kinase is the key step that leads to the release of the polymerase from the promoter, allowing it to initiate transcription. This phosphorylation alters the conformation of RNA polymerase II, enabling it to begin elongating the RNA transcript.

Question 17

All of the following are required for eukaryotic transcription in vitro except
A) TAF.
B) TFIIE.
C) TBP.
D) Mediator.

Accepted Answer

All of the other factors listed (TAF, TFIIE, TBP) are required for eukaryotic transcription in vitro, but Mediator is not always required for transcription in vitro. While it is often present and involved in transcriptional regulation, it is not an essential component for the core transcription machinery.

Question 18

Processing of pre-tRNAs to produce tRNAs involves
A) cleavage of the pre-tRNA.
B) CCA addition to the 5ʹ end.
C) phosphodiesterase activity to cleave the base and deoxyribose.
D) the removal of one intron.

Accepted Answer

The answer of Processing of pre-tRNAs to produce tRNAs involves
A)...

Question 19

Processing of RNA transcripts occurs
A) only in eukaryotic cells.
B) only with mRNA transcripts.
C) only with rRNA and mRNA transcripts.
D) with tRNA, rRNA, and mRNA transcripts.

Accepted Answer

Processing of RNA transcripts occurs with all three types of RNA molecules (tRNA, rRNA, and mRNA) in both prokaryotic and eukaryotic cells.

Question 20

Self-splicing was discovered in studies of the
A) pre-mRNAs of Tetrahymena.
B) pre-mRNAs of E. coli.
C) pre-rRNA of Tetrahymena.
D) pre-rRNA of E. coli.

Accepted Answer

Self-splicing was discovered in studies of the pre-rRNA of Tetrahymena, a type of single-celled eukaryote. This process involves the RNA molecule catalyzing its own excision from a larger RNA precursor, a groundbreaking discovery that highlighted the catalytic capabilities of RNA.

Quiz 8: RNA Synthesis and Processing

The prokaryotic cells most commonly used to study transcription and translation are from

RNA polymerase differs from DNA polymerase in that it

The DNA sequence to which an RNA polymerase binds to initiate transcription of a gene is called a(n)

The regions of the DNA where RNA polymerase binds can be identified by

The role of the sigma ( $\sigma$ ) factor in prokaryote transcription is to

Transcription of a bacterial gene is initiated

The sigma ( $\sigma$ ) subunit of bacterial RNA polymerase remains associated for the addition of _______ during transcription.

Transcription is _-dependent _ synthesis.

Termination of transcription in E. coli is signaled by

Eukaryotic RNA polymerase I genes code for

Mitochondrial genes are transcribed by

The large multi-subunit complex that links the general transcription factors to the gene-specific transcription factors is called

A major difference between eukaryotic and prokaryotic RNA polymerases is that eukaryotic polymerases

The TATA box is similar to the _______ in E. coli.

The first step in the formation of a transcription complex for mRNA transcription is the binding of _______ to the TATA box.

Release of RNA polymerase II to initiate transcription appears to be the direct result of the

All of the following are required for eukaryotic transcription in vitro except

Processing of pre-tRNAs to produce tRNAs involves

Processing of RNA transcripts occurs

Self-splicing was discovered in studies of the