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.

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.

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.

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.

複選題29. Which of the following statements is correct regarding clustered regularly interspaced short palindromic repeats (CRISPR)? (A) CRISPR is found in the eukaryotic genome. (B) A CRISPR locus consists of 2 major components: repeated and spacer sequences. (C) The spacer sequences are acquired from infecting viruses. (D) Cas1 and Cas2 are involved in processing of CRISPR RNA (crRNA). (E) The CRISPR/Cas6 system is currently the most widely utilized tool for genome

30. Which of the following statements is correct regarding small RNA-mediated silencing pathways in eukaryotes? (A) Piwi-interaction RNAs (piRNAs) are expressed predominantly in vegetative cells. (B) Both small interfering RNAs (siRNAs) and microRNAs (miRNAs) are generated from longer RNA molecules by Dicer. (C) The major component of the RNA-induced silencing complex is called Drosha. (D) The size of small RNAs is typically in the range of 30-40 nucleotides. (E) The miRNA is typically highly specific with only one mRNA target. editing.