44. Synthesis of pre-rRNA occurs in the
(A) cytoplasm.
(B) endoplasmic reticulum.
(C) extranucleolar area of the nucleus.
(D) nucleus.
(E) nucleolus.

40. Proteins that bind to DNA and turn on operons by making it easier for RNA polymerase to bind to a promoter are called (A) promoters. (B) operators. (C) activators. (D) inducers. (E) enhances.

41. A typical eukaryotic cell may contain tens of thousands of genes, but only a small fraction of them are expressed at the same time. In this case, (A) the default state of most genes is usually set to be on. (B) the default state of most genes is usually set to be off. (C) most un-expressed genes are deleted from the genome. (D) most expressed genes are copied several times. (E) most expressed genes are joined together.

42. Splice sites in pre-mRNA are marked by two universally conserved sequences contained (A) in the middle of the intron. (B) in the middle of the exon. (C) at the ends of the exons. (D) at the ends of the introns. (E) one in the intron and the other in the exon.

43. Which type of RNA participates in nuclear export of mRNA? (A) snRNA (B) miRNA (C) snoRNA (D) tRNA (E) hnRNA

45. If the third base of a codon is U, which of the following bases on the first position of an anticodon is usually NOT allowed? (A) A (B) G (C) I (D) U (E) any bases are allowed.

46. Active mTOR stimulates the overall rate of protein synthesis in the cell. Which of the following can activate mTOR? (A) presence of stress (B) presence of growth factors (C) low nutrients (D) low energy (E) none of the above

47. Lipid soluble hormones activate transcription by (A) binding to a nuclear receptor. (B) phosphorylating a protein kinase. (C) binding to specific cell-surface receptors. (D) inhibiting a histone deacetylase. (E) none of the above.

48. Which of the following RNA is NOT produced by RNA polymerase II? (A) rRNA (B) mRNA (C) snRNA (D) miRNA (E) none of the above.

49. Which of the following sequences functions as a promoter for transcription? (A) TATA box (B) initiator (C) CpG island (D) all of the above (E) none of the above

50. Eukaryotic mRNA can be degraded in the cell through the following pathways, EXCEPT (A) decapping. (B) poly( A ) shortening. (C) endonucleolytic cleavage. (D) restriction digestion. (E) exonucleolytic cleavage.