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.

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.

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.

23 Which of the following statements is correct regarding translation termination in eukaryotes? (A) The structure and amino acid sequence of the Class I eukaryotic release factors (eRFs) are similar with those of the Class I release factors in prokaryotes. (B) eRF1 induces release of the nascent polypeptide from the peptidy1-transferase center. (C) Rlil is an ATP-binding protein and brings eRF 1 to the ribosome. (D) eRF3 is a GTP-binding protein and catalyzes release of eRF1 from the A-site. (E) Neither eRF1 nor eRF3 participates in separation of the large and small ribosomal subunits after release of the nascent polypeptide.

24. Both the catabolite activator protein (CAP) and the Lac repressor can bind DNA, but why does CAP facilitate transcription while the Lac repressor represses transcription? (A) CAP and the Lac repressor use different structural motifs to bind DNA. (B) CAP binds to the region overlapping the promoter, while the Lac repressor binds to the region at a distance from the promoter. (C) The Lac repressor can interact with the RNA polymerase to inhibit transcription. (D) CAP has an activating surface that recruits the RNA polymerase. (E) CAP binds as a homodimer, while the Lac repressor binds as a homotetramer.

25. Which of the following is the key bacteriophage X regulatory protein that acts as an activator and establishes lysogeny upon infection of a new host? (A) CI. (B) CI. (C) CIII. (D) Cro. (E) Q

26. Which of the following DNA binding domains or motifs is found in most bacterial regulatory proteins? (A) Zinc-finger domain. (B) Basic leucine zipper motif. (C) AT-hook motif. (D) Helix-turn-helix motif. (E) Helix-loop-helix motif.

27. High throughput sequencing technologies become powerful tools to study molecular biology on a genome-wide scale. Which of the following sequencing techniques is used to assess the translational status? (A) RNA binding protein immunoprecipitation-sequencing (RIP-Seq). (B) Chromatin immunoprecipitation-sequencing (ChIP-Seq). (C) Global run-on sequencing (GRO-Seq). (D) 4-thiouridine sequencing (4sU-Seg). (E) Ribosome sequencing (Ribo-Seq).

複選題28. Which of the following statements is correct regarding riboswitches? (A) Most riboswitches are trans-regulatory elements. (B) Riboswitches can regulate gene expression at both transcriptional and translational levels. (C) The riboswitch region that binds the small-molecule ligand is called the receptor. (D) Riboswitches are typically found downstream of genes involved in the synthesis of the metabolite ligand recognized by the riboswitch. (E) Riboswitches can mediate rho-dependent transcription termination.