31. What is the molecular event by which the operator of an operon regulates the expression of its structural gene(s)?
(A) The operator codes for the repressor, which binds to the structural genes
(B) The operator codcs for the repressor, which binds to the RNA polymerase
(C) The operator is bound by the repressor, thereby inhibiting RNA polymerase
(D) The operator is bound by the regulator gene, thereby inhibiting RNA polymerase

27. All of the following groups, when added to histones, can result in an enhanced transcription EXCEPT (A) Phosphate (B) Acetyl (C) Phenyl (D) Methyl

28. What does the binding of a probe to the membrane in a Northern blot indicate (A) The desired DNA sequence is present in the sample (B) The desired RNA sequence is present in the sample (C) The desired protein is present in the sample (D) The desired amino acid scquence is present in the sample

29. What governs the sequence by which tRNAs convey amino acids to mRNA (A) The attractivencss between an mRNA codon and an anino acid on tRNA (B) The attractiveness between an mRNA codon and a tRNA anticodon (C) The attractiveness between an mRNA anticodon and a tRNA codon (D) The attractiveness between an mRNA anticodon and an amino acid on tRNA

30. Producing 100,000 different proteins from 20,000 genes delineates (A) Alternative splicing (B) DNA repair (C) Post-translation modification (D) Elongation

32. What is the best statement regarding protein folding? (A) Protein folding increases the entropy of the system, thus it follows the 2nd law of thermodynamics (B) Protein folding decreases the entropy of the system, thus it follows the 2'd law of thermodynamics (C) Protein folding increases the entropy of the system, thus it violates the 2nd law of thermodynamics (D) Protein folding decreases the entropy of the system, thus it violates the 2'd law of thermodynamics

33. A 10-year-old girl is brought by her parents to the dermatologist. She has many freckles on her face, neck, arms, and hands, and the parents report that she is unusually sensitive to sunlight. Two basal cell carcinomas are identified on her face. Based on the clinical picture, which of the following processes is most likely to be defective in this patient? (A) Removal of pyrimidine dimers from DNA by nucleotide excision repair (B) Removal of mismatched bases from the 3'-end of Okazaki fragments by a methyl-directed process (C) Repair of double-strand breaks by error-prone homologous recombination (D) Removal of uracil from DNA by base excision repair

34. During RNA synthesis, the DNA template sequence TAGC would be transcribed to produce which of the following sequences? (A) ATCG (B) CGTA (C) AUCG (D) GCUA

35. Methylation and subsequent deamination of cytosine produces what type of mutation after one round of DNA replication? (A) C-to-T transversion (B) C-to-T transition (C) G-to-A transition (D) C-to-A transversion HSING UNI

36. As a measure of quality control in translation, which component of the translation machinery is capable of proofreading and editing amino acids? (A) the ribosome (B) Aminoacyl-tR.NA synthetases (C) tRNAs (D) RNA polymerase

37. The hydrogen bonding interactions in a Watson-Crick AT base-pair involve what units in the adenine base? (A) N-1 and the amino group on C-6 (B) N-1 and N-3 (C) N-7 and the amino group on C-6 (D) N-7 and C-8