20. Which of the following statements is correct regarding imprinting?
(A) Imprinting follows the rules of Mendelian inheritance.
(B) Histone acetylation is responsible for imprinting.
(C) Maintenance methyltransferase is involved in the imprinting process.
(D) Sickle cell disorder is a disorder associated with imprinting.
(E) Maintenance of the lysogenic state via cell division is an example of imprinting.

16. Which region of tRNA is responsible for base pairing between tRNA and mRNA? (A) Acceptor stem. (B) Variable loop. (C) Anticodon loop. (D) D loop. (E) YU loop.

17. How does nonsense suppression work? (A) Point mutation of the nucleotide close to the nonsense codon. (B) RNA editing on the nonsense codon. (C) Insertion of a nucleotide during the gene replication. (D) Mutation of a tRNA so that it can bind with the nonsense codon. (E) Mutation of a release factor so that it cannot terminate translation.

18. What is the inducer of the lac operon and binds to the Lac repressor? (A) Lactose. (B) Glucose. (C) IPTG. (D) X-gal. (E) GABA.

19. The first codon of mRNA translated by a ribosome is typically: (A) UGA. (B) GUA. (C) AGU. (D) AUG. (E) AAA.

21. The λ repressor encoded by the cI gene can act as a repressor or an activator. How does the λ repressor act as an activator to stimulate transcription of the cI gene? (A) It binds to OR2 and contacts RNA polymerase at PRM to stimulate transcription. (B) It binds to OR3 and contacts RNA polymerase at PR to stimulate transcription. (C) It binds to OL2 and contacts RNA polymerase at PLM to stimulate transcription. (D) It binds to OL3 and contacts RNA polymerase at PL to stimulate transcription. (E) It binds to ORE and contacts RNA polymerase at PRE to stimulate transcription.

22. Which of the following nucleotides is hydrolyzed in both transcription and in translation elongation? (A) ATP. (B) CTP. (C) GTP. (D) TTP. (E) UTP.

23. Which of the following do NOT typically interact with an elongating RNA polymerase II? (A) Histone-modifying enzymes. (B) Chromatin remodeling complexes. (C) Mediator complexes. (D) Capping enzymes. (E) Histone chaperones.

複選題24. An enhancer: (A) is a trans-acting sequence that stimulates transcription. (B) cannot activate a promoter upstream from this same enhancer. (C) can be located at any distance from a promoter. (D) activates a promoter via an insulator between the enhancer and the promoter. (E) directly interacts with RNA polymerase II to stimulate transcription.

25. Which enzyme is generally linked to transcriptional activation in eukaryotes? (A) Histone methyltransferase. (B) Histone acetyltransferase. (C) Histone phosphorylase. (D) Histone demethylase. (E) Histone deacetylase.

26. Which enzyme is responsible for transcriptional silencing in eukaryotes? (A) DNA methylase. (B) DNA acetylase. (C) DNA polymerase. (D) DNA ligase. (E) DNA endonuclease.