Chapter 26: RNA Metabolism MCQ

2. Which of the following statements about E. coli RNA polymerase is false? A) Core enzyme selectively binds promoter regions, but cannot initiate synthesis without a sigma factor. B) RNA polymerase holoenzyme has several subunits. C) RNA produced by this enzyme will be completely complementary to the DNA template. D) The enzyme adds nucleotides to the 3' end of the growing RNA chain. E) The enzyme cannot synthesize RNA in the absence of DNA.

A

20. Which of the following statements about the synthesis of rRNA and tRNA in E. coli is true? A) Both rRNA and some tRNAs are part of the same primary transcript. B) Each rRNA sequence (16S, 23S, 5S) is transcribed as a separate primary transcript. C) Primary tRNA transcripts undergo methylation, but rRNA sequences are not methylated. D) The tRNA sequences all lie at the 3'end of the rRNA transcripts. E) There is a single copy of the rRNA genes.

A

21. Which of the following is not involved in mRNA processing in vertebrates? A) 30S pre-rRNA B) The nucleoleus C) Ribonucleases D) snoRNAs. E) snoRNPs

A

1. RNA polymerase: A) binds tightly to a region of DNA thousands of base pairs away from the DNA to be transcribed. B) can synthesize RNA chains without a primer. C) has a subunit called lambda, which acts as a proofreading ribonuclease. D) separates DNA strands throughout a long region of DNA (up to thousands of base pairs), then copies one of them. E) synthesizes RNA chains in the 3'--->5' direction.

B

10. Which of the following is not a characteristic of the -terminator in E. coli? A) The rho-terminator has an ATP-dependent RNA-DNA helicase activity. B) The rho-terminator migrates in the 3'-5' direction along RNA. C) The rho-terminator causes RNA polymerase release at a CA-rich sequence near the end of the transcript. D) ATP is hydrolyzed by the rho-terminator during the termination process. E) All of the above are characteristics of the rho-terminator.

B

11. Which of the following is not known to be involved in initiation by eukaryotic RNA polymerase II? A) DNA helicase activity B) DNA polymerase activity C) Formation of an open complex D) Protein binding to specific DNA sequences E) Protein phosphorylation

B

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

B

15. The excision (splicing) of many group I introns requires, in addition to the primary transcript RNA: A) a cytosine nucleoside or nucleotide and a protein enzyme. B) a guanine nucleoside or nucleotide (only). C) a protein enzyme only. D) a small nuclear RNA and a protein enzyme. E) ATP, NAD, and a protein enzyme.

B

18. Which one of the following is not true of the mRNA for calcitonin? A) Exons are used for polypeptide synthesis. B) Introns are complementary to their adjacent exons and will form hybrids with them. C) The mature mRNA is substantially shorter than the corresponding region on the DNA. D) The mRNA is originally synthesized in the nucleus, but ends up in the cytoplasm. E) The splicing that yields a mature mRNA occurs at very specific sites in the RNA primary transcript.

B

5. The sigma factor of E. coli RNA polymerase: A) associates with the promoter before binding core enzyme. B) combines with the core enzyme to confer specific binding to a promoter. C) is inseparable from the core enzyme. D) is required for termination of an RNA chain. E) will catalyze synthesis of RNA from both DNA template strands in the absence of the core enzyme.

B

6. After binding by E. coli RNA polymerase, the correct order of events for transcription initiation is: A) closed complex formation, open complex formation, promoter clearance, start of RNA synthesis. B) closed complex formation, open complex formation, start of RNA synthesis, promoter clearance. C) open complex formation, closed complex formation, start of RNA synthesis, promoter clearance. D) start of RNA synthesis, closed complex formation, open complex formation, promoter clearance. E) start of RNA synthesis, open complex formation, closed complex formation, promoter clearance.

B

7. Which one of the following statements about E. coli RNA polymerase (core enzyme) is false? A) It can start new chains de novo or elongate old ones. B) It has no catalytic activity unless the sigma factor is bound. C) It uses nucleoside 5'-triphosphates as substrates. D) Its activity is blocked by rifampicin. E) Its RNA product will hybridize with the DNA template.

B

14. The 5'-terminal cap structure of eukaryotic mRNAs is a(n): A) 7-methylcytosine joined to the mRNA via a 2',3'-cyclic linkage. B) 7-methylguanosine joined to the mRNA via a 5' 3' diphosphate linkage. C) 7-methylguanosine joined to the mRNA via a 5' 5' triphosphate linkage. D) N6-methyladenosine joined to the mRNA via a 5' 5' phosphodiester bond. E) O6-methylguanosine joined to the mRNA via a 5' 5' triphosphate linkage.

C

24. Which of the following is not usually essential for the catalytic activity of ribozymes? A) Correct base pairing B) Correct base sequence C) Correct interaction with protein D) Correct secondary structure E) Correct three-dimensional structure

C

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

C

12. Which of the following is not a known function of TFIIH? A) DNA helicase activity. B) Hydrolysis of ATP. C) Formation of an open complex D) Termination of transcription E) Nucleotide excision repair

D

22. Which of the following is not a post-transcriptional modification in mRNA or tRNA? A) 4-thiouridine B) Pseudouridine C) Dihydrouridine D) Ribouridine E) Ribothymidine

D

25. Which one of the following properties of the L-19 IVS ribozyme is not shared with enzymes that are purely protein? A) It acts as a true catalyst. B) It can be competitively inhibited. C) It displays Michaelis-Menten kinetics. D) It exploits base pairing with internal guide sequences. E) It makes use of covalent and metal ion catalysis.

D

4. RNA polymerase from E. coli (core enzyme alone) has all of the following properties except that it: A) can extend an RNA chain and initiate a new chain. B) is required for the synthesis of mRNA, rRNA, and tRNA in E. coli. C) produces an RNA polymer that begins with a 5'-triphosphate. D) recognizes specific start signals in DNA. E) requires all four ribonucleoside triphosphates and a DNA template.

D

9. Which of the following is (are) characteristic of rho-independent termination of RNA transcription in E. coli? A) The RNA transcript contains self-complementary sequences. B) Three conserved A's in the template strand near the end of the transcript. C) A CA-rich sequence near the end of the transcript. D) Both A and B E) Both A and C

D

16. A branched ("lariat") structure is formed during: A) attachment of a 5' cap to mRNA. B) attachment of poly(A) tails to mRNA. C) processing of preribosomal RNA. D) splicing of all classes of introns. E) splicing of group II introns.

E

17. Splicing of introns in nuclear mRNA primary transcripts requires: A) a guanine nucleoside or nucleotide. B) endoribonucleases. C) polynucleotide phosphorylase. D) RNA polymerase II. E) small nuclear ribonucleoproteins (snRNPs).

E

19. Differential RNA processing may result in: A) a shift in the ratio of mRNA produced from two adjacent genes. B) attachment of the poly(A) tail to the 5' end of an mRNA. C) inversion of certain exons in the final mRNA. D) the production of the same protein from two different genes. E) the production of two distinct proteins from a single gene.

E

23. Which of the following is not part of miRNA formation? A) Pri-miRNA B) Pre-miRNA C) Dicer D) RISC E) Pseudouridine

E

26. Which one of the following statements about mRNA stability is true? A) Degradation always proceeds in the 5' to 3' direction. B) Degradation of mRNA by polynucleotide phosphorylase yields 5'-nucleoside monophosphates. C) In general, bacterial mRNAs have longer half-lives than do eukaryotic mRNAs. D) Rates of mRNA degradation are always at least 10-fold slower than rates of mRNA synthesis. E) Secondary structure in mRNA (hairpins, for example) slows the rate of degradation.

E

8. "Footprinting," or DNase protection, is a technique used to identify: A) a region of DNA that has been damaged by mutation. B) E. coli cells that contain a desired, cloned piece of DNA. C) the position of a particular gene of a chromosome. D) the position of internally double-stranded regions in a single-stranded DNA molecule. E) the specific binding site of a repressor, polymerase, or other protein on the DNA.

E