《生物化学英文版习题》由会员分享，可在线阅读，更多相关《生物化学英文版习题（40页珍藏版）》请在金锄头文库上搜索。
1、I. Fuel MetabolismPART 1: Structure and Function of ProteinDirections: Each of the numbered items or incomplete statements in this section is followed by answers or by completions of the statement. Select the one lettered answer or completion that is best in each case. Questions 9 and 10 Use the str
2、ucture to answer questions 9 and 10： Asp-Ala-Ser-Glu-Val-Arg 9. The C-terminal amino acid of the hexapeptide shown is (A) alanine (B) asparagine (C) aspartate (D) arginine 10. At physiologic pH (7.4), this hexapeptide will contain a net charge of (A) -2 (B) -1 (C) 0 (D) +1 (E) +2 11. Which one of th
3、e following types of bonds is covalent? (A) Hydrophobic (B) Hydrogen (C) Disulfide (D) Electrostatic 13. Which one of the following conditions causes hemoglobin to release oxygen more readily? (A) Metabolic alkalosis (B) Increased production of 2,3-bisphosphoglycerate (BPG) (C) Hyperventilation, lea
4、ding to decreased levels of CO 2 in the blood (D) Replacement of thesubunits with subunits 14. Production of which of the following proreins would be most directly affected in scurvy? (A) Myoglobin (B) Collagen (C) Insulin (D) Hemoglobin 15. The active site of an enzyme (A) is formed only after addi
5、tion of a specific substrate (B) is directly involved in binding of allosteric inhibitors (C) resides in a few adjacent amino acid residues in the primary sequence of the polypeptide chain (D) binds competitive inhibitors 16. An enzyme catalyzing the reaction E + S = ES E + P was mixed with 4 mM sub
6、strate. The initial rate of product formation was 25% of Vm. The Km for the enzyme is (A) 2 mM (B) 4 mM (C) 9 mM (D) 12 mM (E) 25 mM 17. The velocity (v) of an enzyme-catalyzed reaction (A) decreases as the substrate concentration increases (B) is lowest when the enzyme is saturated with substrate (
7、C) is related to the substrate concentration at lh Vm (D) is independent of the pH of the solution Questions 18 and 19 Refer to the following reaction when answering questions 18 and 19. Fumarate + H20 malate fumarase 18. Fumarase catalyzes the conversion of fumarate to malate. It has a Km of 5 M fo
8、r fumarate and a Vmax of 50 mol/min/mg of protein when measured in the direction of malate formation. The concentration of fumarate required to give a velocity of 25 mol/min/mg protein is (A) 2 M (B) 5 M (C) 10 M (D) 20 M (E) 50 M 19. The Km for fumarase is approximately 5 M for fumarate. The fumara
9、te concentration in mitochondria is approximately 2 mM. If the fumarate concentration dropped to 1 mM, the reaction rate would (A) increase slightly (B) decrease slightly (C) decrease by one half (D) stay exactly the same 20. Hexokinase and glucokinase both catalyze the phosphorylation of glucose to
10、 glucose 6-phosphate. The values of Km for the enzymes are 10 M and 0.02 M, respectively. If blood glucose is 5 mM under fasting conditions and 20 mM after a high-carbohydrate meal (A) hexokinase will function near its Vmax under fasting conditions (B) glucokinase will function near its Vmax under f
11、asting conditions (C) hexokinase will function at less than one-half Vmax after a high-carbohydrate meal (D)glucokinase will function at less than one-half Vmax after a high-carbohydrate meal 21. A competitive inhibitor of an enzyme (A) increases Km but does not affect Vmax (B) decreases Km but does
12、 not affect Vmax (C) increases Vmax but does not affect Km (D) decreases Vmax but does not affect Km (E) decreases both Vmax and Km Questions 22-25 Refer to the graph when answering questions 22-25. 22. The value of Km for the enzyme depicted by curve A is (A) 0.5 mM (B) 1 mM (C) 2 mM (D) 1 mol/min/
13、mg (E) 10 mol/min/mg 23. The value of Vm for the enzyme depicted by curve A is (A) 0.1 mol/min/mg (B) 1 mol/min/mg (C) 10 mol/min/mg (D) 0.5 mM (E) 2 mM 24. Curve B depicts the effect of an inhibitor on the system described by curve A. This inhibitor (A) is a competitive inhibitor (B) is a noncompet
14、itive inhibitor (C) increases the Vmax (D) decreases the Km 25. Curve C depicts the effect of a different inhibitor of the system described by curve A. This second inhibitor (A) is a competitive inhibitor (B) is a noncompetitive inhibitor (C) increases the Vmax (D) decreases the Km answer：DBC BBDD C
15、BBAA ACABDirections: Each group of items in this section consists of lettered options followed by a set of numbered items. For each item, select the one lettered option that is most closely associated with it. Each lettered option may be selected once, more than once, or not at all. Questions 33-37 Match each characteristic below with the protein it best describes. (A) Hemoglobin (B) Myoglobin (C) Collagen (D) Insulin 33. Requires vitamin C for its synthesis 34. Has one oxygen binding site and one polypeptide chain 35. Contains f
