33. The steady state assumption, as applied to enzyme kinetics, implies:
(A) the ES complex is formed and broken down at equivalent rates.
(B) the enzyme is regulated.
(C) K_m=K_s.
(D) the Km is equivalent to the cellular substrate concentration.
(E) the maximum velocity occurs when the enzyme is saturated. 

29. A protein mixture contains proteins A, B, and C (Protein A: homodimer M. = 140,000, pI 8； Protein B: Mr = 113,000, pI 5； Protein C: Mr = 13,000, pI 9). 1. Sandy used SDS-PAGE to separate theses three proteins. The sequence of the protein bands shown in gel from top to bottom is A-B-C. 2. Simon dissolved the protein mixture in 20 mM phosphate buffer (pH 7) and loaded to a cation exchange column equilibrated with the same buffer. Protein B could not bind to the column.  3. Samuel dissolved the protein mixture in 20 mM phosphate bufter (pH 7) and loaded to an anion exchange column equilibrated with the same buffer. Only protein A and C could bind to the column. 4. Silvia used a gel filtration column to separate them, C will be eluted first.  5. Sophie used 2-Dimensional electrophoresis to separate them. The relative positions of these three proteins is like the image below.  (A) 1, 2, and 5 are correct. (B) 2 and 4 are incorrect. (C) 1, 3, and 4 are incorrect.(D) Only 2 is correct.  (E) Only land 3 are incorrect.

30. The following figure describes the torsion angle of the residue i in a protein. What does the figure tell you? (A) It is Φ angle -90 degrce. (B) It isωangle +90 degree. (C) It is Φ angle t90 degree. (D) It is φ angle -90 degree. (E) It is Φ angle +90 degree

31. Which of the following is not correct concerning cooperative binding of a ligand to a protein? (A) It is usually a form of allosteric interaction. (B) It is usually associated with proteins with multiple subunits. (C) It results in a sigmoidal binding curve. (D) It rarely occurs in enzymes. (E) It results in a nonlinear Hill Plot.

32. In the following diagram of the first step in the reaction catalyzed by the protease chymotrypsin, the process of general base catalysis is illustrated by the number__________ , and the process of covalent catalysis is illustrated by the number ____________.(A) 3；2 (B) 1；3 (C) 2；3 (D) 2； 1

34. Which one of the following statements is correct? 1. Conversion of ethanol to acetaldehyde is a two-electron oxidation.  2. FAD is a stronger reducing reagent than NAD+.  3. There is entropy loss when ADP is phosphorylated.  4. Creatine phosphate is a high-energy-bond containing molecule.  5. NAD+ is the electron acceptor during in the conversion of 3-phosphoglycerate to 1,3-bisphosphoglycerate. (A) 1, 2, and 3 are correct. (B)2, 3, and 4 are correct. (C)1, 3, and 4 are correct. (D) 1,3, 4, and 5 are correct. (E)2, 3, 4, and 5 are correct.

35. Which of the following statements is incorrect? (A) 2, 3, and 5 are incorrect. (B) 1, 3, and 4 are incorrect. (C) 1,3, and 5 are incorrect. (D) All are incorrect. (E) None is incorrect.

36. Which statement regarding glycogen breakdown is correct?  1. Cleavage of glycogen terminal glucose is catalyzed by glycogen phosphorylase.  2. The breaksdown of glycogen to generate Glucose-6-phosphate needs no ATP. 3. Transferase activity in glycogen debranching enzyme catalyzes the transfer of shorter α(1→)6 linked glucose chain to another o(1-)6 linked glucose chain for further cleavage reaction. 4. Glucosidase activity in glycogen debranching enzyme catalyzes the cleavage ofα(1→6) linked glucose for complete breaking down the branch in glycogen (A) 1, 2, and 3 are correct. (B) 2, 3, and 4 are correct. (C) 1, 2, and 4 are correct. (D) All are correct. (E) None is correct.

37. Which one of the following statements is incorrect? (A) P-type ATPase transporter is inhibited by vanadate. (B) Cyanide (CN-) blocks the lactose transporter in E.coli. (C) Tetradotoxin impairs voltage-gated Na+ channels. (D) Statin competes with acetyl Co-A. (E) Aspirin inhibits COX-2. pyruvatc

38. Which one is incorrect? (A) Catabolisin of fatty acids produces acetyl-CoA. (B) Catabolism of fatty acids produces reducing power NADH. (C) Anabolism of fatty acids requires acetyl-CoA and malonyl-CoA. (D) Anabolism of fatty acids requires reducing power from NADPH. (E) Fatty acid synthase contains a domain of acyl-CoA dehydrogenase.

39. Which one is not a rate-limiting step in lipid metabolism? (A) Carnitine acytransferase I for fatty acid entry into mitochondria (B) Acetyl-CoA carboxylase for biosynthesis of fatty acid (C) PEP carboxykinasc for triacylgiycerol cycle (D) Acyl transferase for phospholipid synthesis (E) HMG reductase for cholesterol synthesis