Quiz 6

Which of the following does E. coli RNA polymerase resemble on a molecular level? A right hand A left hand A crab claw A snowplow None of the above

A crab claw

The carboxy-terminal domain (CTD) of RNA polymerase II is that portion of the polymerase that is involved in: The initiation of DNA transcription The capping of the RNA transcript The attachment to the spliceosome for RNA splicing. All of the above

All of the above

Which of the following post-transcriptional processes can lead to the production of multiple protein isoforms from a single gene? Alternative splicing Capping Nonsense mediated decay Polyadenylation RNA interference

Alternative splicing

To what position of the pyrimidine is the uracil attached in pseudouridine, a base commonly found in tRNA? 1 2 3 4 5

5

Which of the following best describes the structure of the mRNA cap? guanosine, attached via a 5'-3' monophosphate linkage guanosine, attached via a 5'-5' triphosphate linkage 7-methylguanosine, attached via a 5'-3' monophosphate linkage 7-methylguanosine, attached via a 5'-3' triphosphate linkage 7-methylguanosine, attached via a 5'-5' triphosphate linkage

7-methylguanosine, attached via a 5'-5' triphosphate linkage

How does cellular RNA synthesis differ from DNA synthesis? DNA is always synthesized with a lower fidelity than RNA DNA synthesis is template directed and RNA synthesis is not DNA synthesis requires a primer, RNA synthesis does not RNA polymerase requires Mg2+, DNA polymerase does not None of the above

DNA synthesis requires a primer, RNA synthesis does not

Which of the following statements about bacterial mRNA is true? An mRNA molecule cannot begin to direct protein synthesis until it is completed, because the point of ribosomal binding for polypeptide initiation is always near the end of the mRNA synthesized last. The codon signaling peptide termination should be located in the mRNA near the 5' end. Once synthesized by the bacterium this mRNA is never degraded, but is passed on to the daughter cells at cell division. During polypeptide synthesis, ribosomes move along the mRNA in the 5' to 3' direction. The Shine-Dalgarno sequence is required for termination of translation.

During polypeptide synthesis, ribosomes move along the mRNA in the 5' to 3' direction.

When is a branched ("lariat") structure is formed during RNA processing? During attachment of a 5' cap to mRNA. During attachment of poly(A) tails to mRNA. While processing of preribosomal RNA. When all classes of introns are spliced. During splicing of group II introns.

During splicing of group II introns.

What is removed from the RNA Primary Transcript in order to produce mRNA? TATA boxes Recombination Signal Sequences Introns Promoter sites Polyadenylation

Introns

How does the rho helicase terminate transcription? It acts as a protease, cleaving the ω (Omega) subunit of the RNA polymerase It acts as a helicase, pulling the RNA from the transcription complex It acts as a kinase, phosphorylating the CTD of the alpha subunit It acts as a phosphatase, de-phosphorylating the CTD of the alpha subunit of RNA polymerase

It acts as a helicase, pulling the RNA from the transcription complex

Which of the following best describes the structure of the mRNA cap? guanosine, attached via a 5'-3' monophosphate linkage guanosine, attached via a 5'-5' triphosphate linkage 7-methylguanosine, attached via a 5'-3' monophosphate linkage 7-methylguanosine, attached via a 5'-3' triphosphate linkage 7-methylguanosine, attached via a 5'-5' triphosphate linkage

NOT 7-methylguanosine, attached via a 5'-3' triphosphate linkage

Which of the following statements concerning transcription is false? Initiation of transcription requires several steps generally divided into two phases, binding and initiation. In the binding phase, the initial interaction of the RNA polymerase with the promoter leads to formation of a closed complex, in which the promoter DNA is stably bound but not unwound. A 12 to 15 bp region of DNA—from within the -10 region to position +2 or +3—is unwound to form an open complex. Once elongation commences, the alpha subunit is released and the polymerase leaves the promoter and RNA polymerase becomes committed to elongation of the RNA.

NOT A 12 to 15 bp region of DNA—from within the -10 region to position +2 or +3—is unwound to form an open complex.

How do Group I introns differ from Group II introns, and introns removed by the spliceosome? In case of group I intron splicing, the nucleophile in the first transesterification is a 2' hydroxyl. In case of group I intron splicing, splicing does not require a protein catalyst. In case of group I intron splicing, the intron is not composed of RNA only. In case of group I intron splicing, the nucleophile in the first transesterification is a 3' hydroxyl.

NOT In case of group I intron splicing, splicing does not require a protein catalyst.

How does the rho helicase terminate transcription? It acts as a protease, cleaving the ω (Omega) subunit of the RNA polymerase It acts as a helicase, pulling the RNA from the transcription complex It acts as a kinase, phosphorylating the CTD of the alpha subunit It acts as a phosphatase, de-phosphorylating the CTD of the alpha subunit of RNA polymerase

NOT It acts as a protease, cleaving the ω (Omega) subunit of the RNA polymerase

Which of the following is not a property of a rho-independent terminator sequence? The DNA is palindromic The coding strand can form a hairpin The template strand can form a hairpin The coding strand is G-rich The template strand is A-ric

NOT The DNA is palindromic

Which of the following best describes the role of sigma factor of E. coli RNA polymerase? Sigma factor associates with the promoter before binding core enzyme. Sigma factor combines with the core enzyme to confer specific binding to a promoter. Sigma factor is inseparable from the core enzyme. Sigma factor required for termination of an RNA chain. Sigma factor will catalyze synthesis of RNA from both DNA template strands in the absence of the core enzyme.

Sigma factor combines with the core enzyme to confer specific binding to a promoter.

Which of the following is needed for chemical modifications of mainly ribosomal RNAs, transfer RNAs and small nuclear RNAs? Small nuclear ribonucleic acid (snRNA) Small nucleolar RNA (snoRNA) MicroRNA (miRNA) Guide RNA (gRNA)

Small nucleolar RNA (snoRNA)

What is the role of the U1 snRNP in the spliceosome? The U1 snRNP recognizes and binds to the sequence of the 5'-splice site of an intron in a strand of pre-mRNA. The U1 snRNP recognizes and binds to the sequence of the 3'-splice site of an intron in a strand of pre-mRNA. The U1 snRNP recognizes and binds the branch point "A" of an intron in a strand of pre-mRNA. The U1 snRNP catalyzes transesterification reactions

The U1 snRNP recognizes and binds to the sequence of the 5'-splice site of an intron in a strand of pre-mRNA.

Which of the following statements about E. coli RNA polymerase (core enzyme) is false? In the absence of the sigma subunit, core polymerase has little specificity for where initiation begins. The core enzyme contains several different subunits. The core enzyme has no polymerizing activity until the sigma subunit is bound. The RNA chain grows in a 5' to 3' direction. The RNA product is complementary to the DNA template.

The core enzyme has no polymerizing activity until the sigma subunit is bound.

Processing of a primary mRNA transcript in a eukaryotic cell does not normally involve: attachment of a long poly(A) sequence at the 3' end. conversion of normal bases to modified bases, such as inosine and pseudouridine. excision of intervening sequences (introns). joining of exons. methylation of one or more guanine nucleotides at the 5' end.

conversion of normal bases to modified bases, such as inosine and pseudouridine.

Spliceosomes are primarily composed of which of the following types of RNA? miRNA siRNA snRNA rRNA tRNA

snRNA

Which of these processes does not occur in the nucleus of eukaryotes? polyadenylation. 5'-end capping of mRNAs. translation. pre-mRNA splicing.

translation.