68. Ubiquitin is a small protein which is covalently linked to proteins designated for destruction via ____.
(A) ATP-dependent proteases in lysosomes
(B) ATP-dependent proteases in proteasomes
(C) ATP-dependent proteases in ribosomes
(D) ATP-independent proteases in endosomes
(E) ATP-independent proteases in peroxisomes

64. 5-phosphoribosyl-1-pyrophosphate (PRPP) is a precursor in the synthesis of all of the following products except ________. (A) histidine (B) tryptophan (C) arginine (D) UMP (E) AMP

65. In eukaryotic cells, mRNA modification includes __________. (A) splicing out exons and join introns (B) add a cap at 3’ end to protect the 3’ end (C) add a phosphate group at 5’ end to increase stability (D) remove nucleotides at 3’ end before addition of a poly A tail (E) remove 3’UU and attach CCA

66. What is the appropriate order for oxidation of glucose to CO2, H2O and ATP? 1.convert pyruvate to acetyl CoA 2.electron-transport chain 3.citric acid cycle 4.oxidative-phosphorylation 5.glycolysis (A) 3→5→1→4→2 (B) 5→1→3→2→4 (C) 1→4→5→2→3 (D) 3→1→4→2→5 (E) 4→1→3→5→2

67. Cooperative binding of a ligand to a protein is a form of allosteric binding. Which of the following statements is false? (A) It is usually associated with proteins with multiple subunits. (B) The binding of one ligand affects the affinities of other unfilled binding sites. (C) The Hill plot results in a hyperbolic curve. (D) It results in a sigmoidal binding curve. (E) Hill coefficient (nH) is a measure of the degree of cooperativity.

69. What of type reaction promotes the conversion of phosphatidylserine to phosphatidylethanolamine? (A) transamination (B) acetylation (C) dehydrogenation (D) methylation (E) decarboxylation

70. What compound does not exist in the glyoxylate cycle? (A) citrate (B) α-ketoglutarate (C) isocitrate (D) malate (E) oxaloacetate

71. Which compound is not one-carbon carrier in metabolism? (A) tetrahydrobiopterin (B) formyl-tetrahydrofolate (C) methyl-tetrahydrofolate (D) biotin (E) S-adenosylmethionine

72. Which of the following statements regarding yeast two-hybrid analysis is false? (A) The goal is to bring together the DNA-binding domain and the activation domain of the yeast Gal4 protein. (B) Gal4 protein has two domains: one that binds a specific DNA sequence domain, the other activates RNA polymerase to synthesize tRNA from an adjacent gene (reporter gene). (C) A library can be set up to fuse to the Gal4 protein DNA-binding domain. (D) The interacting protein can be quickly identified by DNA sequencing of the fusion protein′s gene. (E) Some false positive results occur, due to the formation of multiprotein complexes.

73. What amino acid residues in some membrane-associated proteins are covalently linked to myristoyl or farnesyl groups? (A) asparagine and lysine (B) cysteine and glycine (C) serine and tyrosine (D) asparagine and serine (E) proline and lysine

74. What main component in plasma membrane has the oligosaccharide head groups to determine human blood types (O, A, B, and AB)? (A) caveolin in lipid raft (B) clathrin in apical surface (C) sphingolipid (D) phospholipid (E) cholesterol