109年 - 109 國立台灣大學_碩士班招生考試：生物化學(A)#90652

1. Which of the following amino acid is branched at β-carbon? (A) Leucine (B) Threonine (C) Serine (D) Phenylalanine (E) Histidine

2. Eric uses a computer software to simulate a 20-residue peptide in different structures. Structure A is an α-helix structure; structure B is a β-strand; structure C is a helix in the collagen structure. The length of these structures should be: (A)C＞B＞A (B) C＞A＞B (C) B＞A＞C (D) A＞B＞C (E) B＞C＞A

3. Five students are discussing carbohydrate.

Student A says: Glc(1α

B1 )Fru is sucrose.

Student B s ays: An aldohexose has 16 stereoisomers.

Student C says: Hyaluronate and heparin are sulfated heteropolysaccharides.

Student D says: The α and β anomers of D-glucose can freely interconvert in aqueous solution without breaking any bonds.

Student E says: α -GalNAc is added to the side-chain of asparagine in N-linked glycosylation. How many students are correct? (A) 1 (B) 2 (C)3 (D) 4 (E) 5

4. Five students are discussing hexose structure.

Student A says: D-glucose and b-glucosamine are different on C2.

Student B says: D-glucose and L-glucose are different on C5.

Student C says: D-glucose and D-glucuronic acid are different on C6.

Student D says: a-D-glucose and B-D-glucose are different on Cl.

Student E says: D-glucose and b-galactose are different on C4.

How many students are correct? (A) 1 (B) 2 (C)3 (D) 4 (E) 5

5. Both water and glucose share an–OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explanation is that:

(A) the larger glucose binds better to the enzyme; it induces a conformational change in hexokinase that brings active-site amino acids into position for catalysis. (B) glucose has more –OH groups per molecule than does water. (C) the–OH group of water is attached to an inhibitory H atom, while the glucose –OH group is attached to C. (D) water and the second substrate, ATP, compete for the active site resulting in a competitive inhibition of the enzyme. (E) water normally will not reach the active site because it is hydrophobic.

6. All of the following are characteristics of hemoglobin's binding of oxygen except:

(A) CO₂promotes dissociation of O₂ from hemoglobin by lowering the pH. (B) 2,3-Bisphosphoglycerate and O₂are mutually exclusive allosteric effectors of hemoglobin. (C) 2,3-Bisphosphoglycerate promotes release of O₂ by hemoglobin. (D) CO₂ can bind with hemoglobin's free amino groups and stabilize deoxy-hemoglobin. (E) Protons promote binding of oxygen by hemoglobin.

7. Which of the following is the major advantage of a multi-enzyme complex? (A) It's large size enables it to span an entire membrane. (B) The product of one enzyme is passed directly to the next enzyme without the possibility of difiusion. (C) Multi-enzyme complexes are much less likely to be inhibited. (D) All of the above. (E) None of the above.

8. Glycogen phosphorylase displays allosteric activation and inhibition by multiple modes. Which of the following is a correct relation? (A) Phosphate: positive heterotropic effector. (B) AMP: negative heterotropic effector. (C) ATP: positive heterotropic effector. (D) Glucose-6-phosphate: negative heterotropic effector. (E) Phosphorylation: covalent inhibitor.

9. All are characteristics of molecular motors or motor proteins except: (A) They must be able to associate and dissociate reversibly with a polymeric protein array, a surface or substructure in the cell. (B) They use chemical energy (e.g., ATP) to orchestrate movement. (C) They transfer ATP energy into mechanical energy. (D) ATP bydrolysis is presumed to drive and control protein conformational changes that result in sliding or walking movement of one molecule relative to another. (E) All are true.

10. Which of the following statement regarding Cori cycle and pentose phosphate pathway is false? (A) Cori cycle involves in conversion of lactate produced in the muscle by regeneration of glucose in the liver. (B) Cori cycle involves in conversion of lactate produced in the liver by regeneration of glucose in the muscle. (C) The pentose phosphate pathway provides precursors for the synthesis of nucleotides. (D) The metabolic function of the pentose phosphate pathway is to generate NADPH and pentoses for the biosynthesis of fatty acids and nucleic acids (E) All are correct.

11. Which answer represents the correct order of clectron flow between 1 to 4 factors?

1. Cytochrome c 2. Co-enzyme Q 3. Oxygen 4.NADH

(A) 4,3,2, 1 (B) 4, 1,2,3 (C) 4, 2,1, 3 (D) 2, 1,4, 3 (E) 2, 4, 1, 3

12. Which of the following statements about pyruvate metabolism is correct?

1. △G° of hydrolysing phosphoenopyruvate to pyruvate is negative.

2.Under anaerobic condition, the purpose of reducing pyruvate to lactate is to regene

3. Conversion of glyceral dehyde-3-hosphate to pyruvate involves enolase and pyruvate kinase.

4. The pyruvate dehydrogenase complex uses all of the following as cofactors: NAD+, COA, FAD, lipoic acid, and thiamine pyrophosphate (TPP).

5. Pyruvate carboxylase requires biotin for activity. (A) 1, 2, and 3 are correct. (B) 1, 3, and 5 are correct. (C) 2, 3, and 4 are correct.(D) 2, 4, and 5 are correct. (E) All are correct.

13. Which of the following statements regarding citric acid cycle or glyoxylate cycle is false?

1. One round of citric acid cycle can generate 10 ATP.

2. The catabolism of proteins, carbohydrates, and fatty acids all feed into the citric acid cycle at one or more points.

3. The 2nd step of glyoxylate cycle uses malate synthase to convert 2 glyoxylate to I malate molecule.

4. Glyoxylate cycle takes place in glyox ysomes during plant cells are performing photosynthesis. (A) 1 and 2 are false. (B) 3 and 4 are false. (C) 2 and 3 are false. (D) 2 and 4 are false. (E) None of above is false.

14. NADH,_______ and__________ are products of glycolysis, and the NADH must be recycled to ________before it becomes limiting in glycolysis. (A) ATP; pyruvate; NAD⁺ (B) NAD⁺; ATP; pyruvate (C) ATP; NAD⁺; ATP (D) ATP; pyruvate; lactate (E) None are true.

15. The endoplasmic reticulum bound enzyme that hydrolyzes glucose-6-phosphate to glucose in liver is: (A) glucokinase. (B) glucose oxidase. (C) hexokinase. (D) phosphoglucomutase. (E) glucose-6-phosphatase.

16. If both NADPH and ribose-5-P are needed in the cells which of the following best represents the net reaction of the pentose phosphate pathway? (A) 4 Fruc-6-P +2 glyceraldehyde-3-P →6 ribose-5-P (B) 3 Gluc-6-P +6 NADP⁺→6 NADPH + 3 CO₂ + 2 Fruc-6-P + 1 glyceraldehyde-3-P + 6 H⁺(C) Gluc-6-P + 2 NADP⁺ +2 H₂O → 2 NADPH + CO₂ + ribose-5-P +2 H⁺(D) Gluc-6-P + 12 NADP⁺ +6 H₂O →12 NADPH +. 6 CO₂ + 12 H⁺ + Pi (E) None of the above.

17. Shuttle vectors have the property that they: (A) contain promoters for the expression of the gene. (B) have origins of replication for two different cell types, usually bacteria and yeast. (C) are capable of incorporating very large DNA fragments. (D) contain more than one antibiotic resistant gene. (E) None of the above.

18. All ypes of aminotransferase (also known as transaminase) rely on which of the following cofactorlcoenzyme? (A) Pyridoxal phosphate (B) FAD (C) NADH (D) Thiamine pyrophosphate (E) Biotin

19. Which two amino acids are important for ammonia assimilation(吸收) by an organism? (B) Glu and Asp (A) Glu and Gln (C) Gln and Asn (D) Lys and Trp (E) Lys and Arg

20. Which compound serves as the methy! group donor for biological methylation reactions? (A) Methyl acetate (B) Methy-tetrahydrofolate (C) S-Adenosylmethionine (D) Methanesulfonic acid (E) Methylephedrine

21. Allopurinol is a drug used to treated chronic gout(痛風) because it inhibits_______.(A) ureate oxidase (B) adenosuccinase (C) adenosine deaminase (D) xanthine oxidase (E) guanine deaminase

22. Carbamoyl phosphate synthetase I deficiency is an autosomal recessive metabolic disorder that causes __________to accumulate in the blood. (A) bicarbonate (B) ammonium (C)ADP (D) phosphate (E) CO₂

23. 5-Fluorouracil (5-FU) is used to treat cancers. It is a mechanism-based inhibitor of _________.(A) ribonucleotide reductase (B) thymidylate synthase (C) adenylosuccinate lyase (D) GMP synthetase (E) xanthine oxidase

24. Fatty-acid biosynthesis is vital in all biology. Which statement is correct? (A) The formation of malonyl-CoA requires micronutrient such as Mn²⁺. (B) The fatty-acid chain lengthening occurs either in ribosome or endoplasmic reticulum. (C) Double bonds can be introduced in Golgi body. (D) The carbon source at sites of endoplasmic reticulum is malonyl- ACP. (E) All of the above.

25. What effect would ketone bodies have on blood pH? (A) Neutralize pH (B) Lower pH (D) Fluctuate pH (E) No effect on pH (C) Increase pH

複選題

26. The following figure shows the phi and psi angles of the residue X in a protein. (A) Phi angle is +45 degree. (B) Psi angle is –90 degree.(C) Phi angle is +90 degree. (D) Psi angle is +60 degree. (E) Psi angle is +45 degree.

27. There are three proteins X, Y, and Z in 20 mM Tris (pH 7.0) solution.

1. Protein X is a homoheptamer. Its pI is 9.2. The molecular mass of each subunit of the protein X is 20,000 Da and the subunit's pl is 9.2.

2. Protein Y is a monomeric protein with molecular mass of 93,000 Da and its pl is 4.

3. Protein Z is a homodimer. Its molecular mass is 1 40,000 Da and its pI is 8.

Please choose the correct answer? (A) When this mixture is loaded onto a cation exchange column, only protein Y can bind to the column: (B) When this mixture is loaded onto a size exclusion column, Protein Y is last eluted. (C) When this mixture is analyzed by a SDS- PAGE, the lowest band is protein Y. (D) When this mixture is analyzed by a SDS- PAGE, protein X and 'Z cannot be separated. (E) When this mixture is loaded onto a cation exchange column, protein X is the first eluted protein.

28. There are four peptides. Their sequences are:

The pI value of these four peptides should be (A) A＞B＞D＞C (B) C＞A＞B＞D (C) B＞A＞C>D (D) B＞A＞D＞C (E)A＞B＞C＞D

29. Because the enzymatic reaction rate is determined by the difference in energy between ES and_________ , the tighter binding of the substrate, the_________ the rate of reaction. (D) EXt; higher (A) S; higher (B) P; lower (C) EX+;lower (E) S; lower

30. In the enzyme catalyzed reaction sequence below, can the E- POA intermediate be predicted and why?(A) Yes, the mechanism is a double-displacement reaction. (B) No, the reaction is order single-displacement. (C) No, the reaction is double-displacement. (D) No, the reaction is random single-displacement. (E) None of the above. E:CrP -E + CiP

31. Which of the following statement regarding enzyme regulation is true? (A) Addition of an inhibitor to a V system results in kinetics similar to addition of a competitive inhibitor to a typical hyperbolic system. (B) Allosteric effectors are always more powerful than covalent modification. (C) Addition of an allosteric activator to a K system changes the plot of V vs. [S] from a sigmoidal curve to a more hyperbolic curve. (D) The T state of an enzyme generally has more activity than the R state. (E) None of the above is true.

32. When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is most nearly correct, when applied to the reaction below? (R = 8.315 J/mol‧ K and T = 298 K)? (A) is -1.7 kJhmol. (B) is +1.7 kJ/mol. (C) is incalculably large and positive. (D) is incalculably large and negative. (E) is zero.

33. Which of the following statement regarding citric acid cycle is false? (A) Citric acid cycle is amphibolic because it plays a role in both catabolism and anabolism. (B) The immediate electron acceptor for the majority of the oxidative reactions of the citric acid cycle is NAD⁺. (C) Many intermediates of citric acid cycle are starting points for synthesis of a variety of compounds (D) Animals can use fat or acetate as the carbon source because they can replenish citic acid cycle intermediates by anaplerotic reaction. (E) All of above are false.

34. Which of the following four statements regarding glycolysis and gluconeogenesis is correct?

1. The conversion of 1 mole of frctose 1,6-bisphosphate to 2 mole of pyruvate by the glycolytic pathway results in a net formation of 2 mole of NAD+ and 4 mole of ATP.

2. The step of glycolysis between glyceraldehyde 3-phosphate and 3-phosphoglycerate involves oxidation of NADH to NAD+.

3.Acetate cannot serve as the starting material for the synthesis of glucose via gluconeogenesis in animals.

4. Pyruvate kinase is used in both glycolysis and gluconeogenesis.

5.The oxidation of 3 mole of glucose by the pentose phosphate pathway may result in the production of 3 mole of pentose, 4 mole of NADPH, and 3 mole of CO₂. (A)1 and 2 are correct. (B) 3 and 4 are correct. (C) 3 is correct. (D) 4 is correct. (E) All are correct.

35. Which of the following statements regarding the enzymes involving in citric acid cycle is false?

1. Citrate synthase is inhibited by NADH and succinyl-CoA.

2. Isocitrate dehydrogenase requires TPP, lipoic acid, FAD, and NAD⁺ as cofactors.

3. α-ketoglutarate dehydrogenase is activated by ADP and NAD⁺.

4. Reactions catalyzed by Succinate dehydrogenase can be blocked by malonate.

5. The reaction catalyzed by fumarase is a dehydration reaction. (A) 1 and 3 are false. (B) 2 and 5 are false. (C) 1 and 4 are false. (D) 2 and 3 are false. (E) 4 and 5 are false.

36. Which statement about ATP synthesis in mitochondria is false? (A) To form proton gradient for ATP synthesis in mitochondria requires various proteins that serve as electron carriers to be oriented asymmetrically with respect to the two sides of the inner mitochondrial membrane. (B) The proton gradient that is generated by electron transfer reactions is used to induce a conformational change in the ATP synthase. (C) Evidence for chemiosmotic coupling as the mechanism for ATP synthesis is based on the observation that many different kinds of substances can serve as uncouplers. (D) The Fo part of the ATP synthase serves as a proton channel, and the F part of the ATP synthase is the site of ATP formation. (E) None of above is false.

37. Seven of the ten reactions of glycolysis are reversible (△G near zero) and can be used in reverse of glycolysis for gluconeogenesis. The three irreversible reactions are catalyzed by: (A) hexokinase, phosphoglycerate kinase, and pyruvate kinase. (B) triose phosphate isomerase, phosphoglycerate mutase, and pyruvate kinase. (C) enolase, phosphoglycerate kinase, and phosphofructokinase-1. (D) hexokinase, phosphoglucoisomerase, and glyceraldehyde-3-phosphate dehydrogenase. (E) hexokinase, phosphofructokinase-1, and pyruvate kinase.

38. Addition of water across a double bond, or removal of water to form a double bond, is catalyzed by a suboclass of the lyase class of enzymes. Which of the following glycolytic enzymes would be a lyase? (A) Glyceraldehyde-3-phosphate dehydrogenase (B) Triose phosphate isomerase (C) Phosphoglycerate mutase (D) Hexokinase (E) Enolase

39. If levels of___________ and/or_____________are low， pyruvate is directed primarily into _________； pyruvate is converted into_______for gluconeogenesis.(A) NADH; ATP; glycolysis; oxaloacetate (C) ATP; acetyl-COA; TCA cycle; oxaloacetate (B) ATP; NADPH; glycolysis; acetyl-CoA (D) NAD⁺; acetyl-CoA; TCA cycle; acetyl-CoA (E) ATP; acetyl-CoA; glycolysis; malate