23. Which one is incorrect about transcription factors?
(A) Leucine zipper is a dimer formation domain.
(B) They can bind to specific DNA elements.
(C) They always locate in nuclei.
(D) The gene expression is often regulated by transcription activators more than repressors in eukaryotes.
(E) They may interact with the Mediator complex.

19. Which of the following statements about regulation of the lac operon is true? (A) In the presence of lactose, the lac repressor, lacl, halts production of the enzymes encoded by the lac operon. (B) The gene product of lacZ is ẞ-galactosidase which cleaves lactose into glucose and galactose. (C) Glucose in the growth medium does not affect the inducibility by lactose. (D) Glucose in the growth medium increases the inducibility by lactose. (E) Its expression is regulated mainly at the level of translation.

20. Monozygous twins share a common genotype. According to previous report, gene expression microarray analysis showed the differential transcription profiles between twin pairs. What is not different in twin pairs? (A) 5-methylcytosine DNA (B) Histone acetylation (C) Histone methylation (D) DNA sequences (E) Fingerprint

21. Which statement is incorrect about translation regulation in eukaryotic mRNAs? (A) Translational regulation may play an important role in regulating very long eukaryotic genes. (B) Translational initiation factor eIF2 can be phosphorylated to activate translation. (C) Some proteins bind directly to 3'UTR of mRNA and act as translational repressors. (D) Proteins 4E-BPs are inactivated by phosphorylation. (E) micro-RNAs are able to inhibit translation.

22. There is a protein containing 456 amino acids and encoded by a gene with ten exons. Which statement you can obtain from the statement above? (A) The exon 10 contains 3'UTR of its mRNA. (B) The translation initiation site is located in exon 1. (C) The length of ten exons is 1368 nucleotides. (D) The length of ten exons is 1371 nucleotides. (E) The length of introns is shorter than exons.

24. Which one is NOT a component of pre-replication complex? (A) MCM (B) ORC (C) RPA (D) GINS (E) Cdc45

25. Which core histone does NOT have a variant? (A) H2A (B) H2B (C) H3 (D) H4 (E) H1

26. Which of the following classes of noncoding RNAs is directly involved in RNA interference? 1. siRNA2. snoRNA3. piRNA4. miRNA5. hnRNA (A) 1, 3, 4, 5 are involved. (B) 1, 2, 3, 4 are involved. (C) 1, 4, 5 are involved. (D) 1, 3, 4 are involved. (E) All of the above are involved.

27. Which of the following general statement about a G protein-coupled receptor is true? 　1. It contains twelve transmembrane domains. 　2. It is organized with the N-terminus on the cytoplasmic face of the membrane. 　3. It is organized with the C-terminus on the cytoplasmic face of the membrane. 　4. It is found only in eukaryotes (A) Only 3 is correct (B) 2, 4 are correct. (C) 3, 4 are correct. (D) 1, 2 are correct. (E) 1, 3, 4 are correct.

28. Which one of the following statements about mitochondrial DNA is incorrect? (A) Products of mitochondrial genes are not exported to cytosol (B) All the mitochondria of a developing embryo are derived from the mother's egg (C) Mitochondrial genetic codes differ from the standard nuclear code (D) Mitochondria contain one non-histone mitochondria DNA molecule (E) Mutations in mitochondrial DNA would cause genetic diseases.

29. Which E3 ligase is involved in sister chromatid segregation during mitosis? (A) APC/C (B) RNF8 (C) RNF168 (D) BRCA1 (E) Cul3-KLHL20