16. A special form of RNA editing found in the mitochondria of trypanosomes and mediated by guide RNAs is deletion and insertion of:
(A) adenine.
(B) uracil.
(C) guanine.
(D) cytosine.
(E) inosine.

12. Which of the following complexes specifically recognizes Holliday junctions and promotes branch migration? (A) RecBCD complex. (B) UvrABC complex. (C) ClpPR complex. (D) RuvAB complex.(E) RhlAB complex.

13. Transcription initiation involves recognition of consensus sequences by specific regions/domains of the RNA polymerase in Escherichia coli. Which of the following regions or domains recognizes the -10 promoter element? (A) o factor region 2. (B) o factor region 3. (C) o factor region 4. (D) C-terminal domain of subunit o. (E) N-terminal domain of subunit a.

14. The structural feature of mRNA at the intrinsic transcription terminator in prokaryotes is a hairpin structure followed by: (A) an A-rich sequence. (B) a C-rich sequence. (C) a G-rich sequence. (D) a U-rich sequence. (E) an AU-rich sequence.

15. Which of the following small nuclear ribonucleoproteins (snRNPs) recognizes the 5' splice site? (A) U1. (B) U2. (C) U4. (D) U5. (E) U6.

17. The Drosophila Dscam gene contains 48 alternative forms of exon 6. What is the mechanism for having only one exon 6 variant in the mature mRNA? (A) Splicing factors cannot bind to more than one splicing site due to steric hindrance. (B) Spliced mRNA with more than one exon 6 variant leads to nonsense-mediated RNA decay. (C) The docking site binds to only one selector sequence located upstream of the exon6 variant. (D) Each exon 6 variant contains different sequences at the splicing sites. (E) Only the exon 6 variant that recruits enough SR proteins is retained in the mature RNA.

18. What is the function of the Shine-Dalgarno sequence? (A) It recruits the RNA polymerase. (B) It recruits the core transcription factors. (C) It recruits the initiation factors (D) It recruits the large ribosomal subunit. (E) It recruits the small ribosomal subunit.

19. The first step of tRNA charging catalyzed by the aminoacyl-tRNA synthetase is: (A) Reaction of the amino acid with ATP. (B) Reaction of the amino acid with GTP. (C) Transfer of the amino acid to the 3' end of tRNA. (D) Transfer of the amino acid to the 5' end of tRNA. (E) Binding of the amino acid to the anticodon loop.

20. Which of the following statements is correct regarding upstream open reading frames (uORFs)? (A) uORFs can be found in both eukaryotes and prokaryotes. (B) uORFs can be found in both 5' and 3' untranslated regions. (C) The presence of uORFs typically causes an increase in protein expression. (D) Translation of the open reading frame (ORF) encoding the yeast activator Gcn4 is inhibited when amino acids are deficient, because the ribosome moves slowly along the uORFs and then dissociates. (E) The size of uORFs is typically more than 20 codons.

21. Which of the following bacterial elongation factors (EFs) catalyzes translocation of the tRNA and mRNA and causes conformational changes of the ribosome? (A) EF-Tu. (B) EF-Ts. (C) EF-G. (D) EF-P. (E) EF-4.

複選題22. Which of the following statements is correct regarding the wobble base pair? (A) The wobble base pair follows Watson-Crick base pair rules. (B) The wobble base pair takes place at 3' end of the tRNA anticodon. (C) Hypoxanthine (I) can pair with uracil (U), adenine ( A ), or cytosine ( C ). (D) Guanine (G) can pair with adenine ( A  ) or cytosine ( C ). (E) The Wobble hypothesis predicts that the minimum requirement to satisfy all possible codons is 21 tRNAs.