112年 - 112 國立中山大學碩士班暨碩士在職專班招生考試試題_生科系碩士班乙組：生物化學#118675

1. Which statement MOST COMPLETELY EXPLAINS the large △G° for the hydrolysis of phosphoenolpyruvate? (A)Hydrolysis of the phosphoanhydride bond along with the conversion of the enol to the keto form of pyruvate. (B) The hydrolysis of the phosphoanhydride bond. (C) Conversion from the enol to the keto form of pyruvate. (D) Strong bond energy along with a change in the stereochemistry of the molecule. (E) The large △G° of the phosphoester bond.

複選題
2.Which of the following statements regarding ATP is true? (A) the energy of hydrolysis is the same for all of the phosphate groups of the molecule (B) despite the very exergonic nature of the hydrolysis, ATP does not hydrolyze spontaneously due to a very high activation energy (C) the △G° of hydrolysis within the cell is substantially greater than the △G°' due to a higher concentration of ATP with respect to ADP (D) electrostatic attraction of the phosphate groups contributes to a more exergonic free (E) both b and c are correct energy

3. All are true statements about L-isoleucine EXCEPT: (A) Its enantiomer is named D-isoleucine. (B) L-alloleucine would be its diastereomer. (C) It contains a total of two asymmetric or chiral carbons. (D) It can also be named as (2S,3S)-isoleucine using the (R,S) system. (E) Its diastereomer would be named D-leucine.

4.Which statement is INCORRECT about these amino acids, and amino acid derivatives? (A)GABA (γ-aminobutyric acid) is a potent inhibitory neurotransmitter derived from glutamic acid. (B) Ornithine is an important metabolic intermediate. (C) Epinephrine is a hormone derived from tryptophan. (D) Serotonin is a neurotransmitter derived from tryptophan. (E) Histamine is a neurotransmitter derived from histidine.

5. Homologous proteins such as hemoglobin from different organisms do NOT: (A)have nearly identical lengths. (B) share little sequence homology with other proteins with similar function (e.g., myoglobin). (C) share a significant degree of sequence similarity. (D) perform the same function in different organisms. (E) have sequence identity in direct correlation to the relatedness of the species from which they were derived.

6. All of the statements about the peptide val-asp-trp-asn-ser are correct EXCEPT: (A)This peptide would show a strong absorption band at 280 nm. (B) Reaction with chymotrypsin would yield two peptides. (C) To synthesize this peptide using the solid phase method of Merrifield, the amino acid directly attached to the resin would be serine. (D) After the second round of Edman degradation using the reagent PITC, the PTH-amino acid residue released would be PTH-asp. (E) The peptide is resistant to trypsin.

7. All of the information necessary for folding the peptide chain into its "native" structure is contained in the___________ of the peptide. (A) amino acid sequence (B) amino acid composition (C) configuration (D) amino acid side chain charges (E) all are true

8. Secondary and higher orders of structure are determined by all EXCEPT: (A) hydrophobic interactions. (B) ionic bonds. (C) van der Waals forces. (D) hydrogen bonds. (E) peptide bonds.

9. A β-barrel would most likely be composed of___________ (A) parallel β-sheets connected by regions of a-helix (B) parallel β-sheets connected by β-turns. (C) parallel β-sheets connected by regions of random coil. (D) parallel β-sheets connected disulfide bonds. (E) both a and c are correct.

10. All of the statements about the tertiary structure of the enzyme triose phosphate isomerase are correct EXCEPT: (A) Its β-strands are parallel. (B) Its a-helices are in the interior core of the molecular structure. (C) It contains a β-barrel in the center of its structure. (D) It is composed entirely of alternating o-helices and β-strands. (E) Hydrophobic residues are buried between concentric layers.

11. All of the following statements about the nature of glycogen are true EXCEPT: (A) It is a polysaccharide used for storage. (B) It is a branched polymer of linked glucose residues. (C) It has all non-reducing ends. (D) The highly branched structure allows the rapid mobilization of glucose during metabolic need. (E) It is found primarily in the liver and skeletal muscles.

12. Cellulase is considered a_________. (A) a-(1→4) glucosidase (B) β-(1→4) glucosidase (C) a-(1→6) glucosidase (D) β-(1→4) glucosidase (E) a-(1→1) glucosidase

13. Steroid hormones include all of the following EXCEPT: (A) dolichol. (B) progesterone. (C) cortisol. (D) estradiol. (E) testosterone.

14. Which of the following enzymes is responsible for the release of arachidonic acid from membrane phospholipids? (A) phospholipase A₁ (B) phospholipase A₂ (C) phospholipase B (D) phospholipase (E)phospholipase

15. Which of the following would be the most likely interaction between a peripheral membrane protein that contained a high lysine content and a membrane? (A) ionic interaction (B) hydrophobic interaction (C) hydrogen bonding (D) covalent bonding (E) both a and c

16. The two major phospholipids on the outer leaflet of erythrocytes are: (A) phosphatidylcholine and phosphatidylethanolamine. (B) phosphatidylcholine and sphingomyelin. (C) phosphatidylethanolamine and sphingomyelin. (D) phosphatidylserine and sphingomyelin. (E) phosphatidylcholine and phosphatidylserine.

17. Glycophorin is a membrane protein with: (A) multiple transmembrane segments. (B) most of the mass oriented outside the surface of the cell. (C) about 10% carbohydrate and 90% protein. (D) transmembrane β-barrel segments. (E) All are true

18. Which of the following is true regarding membrane function? (A) a caveola contains a very high concentration of cholesterol and unsaturated phospholipids. (B) scaffolding proteins, particularly those containing BAR domains, result in curvature of the cell membrane. (C) lateral membrane diffusion within a biological membrane is a completely unrestricted process(D)membrane fusion with vesicles is often accomplished with the aid of a SNARE protein.(E)both b and d are correct.

19. All are important functional groups participating in H-bond formation EXCEPT: (A)amino group of the cytosine, adenine and guanine. (B) the ring nitrogens at position 3 of pyrimidines and 1 of purines. (C) the electronegative oxygen atoms. (D) the electron density in the double bonds of the bases. (E) the carbonyl group at position 4 of uracil and thymine, position 2 of cytosine, and position 6 of guanine.

20. All of the following are examples of nucleotide functions EXCEPT: (A) CTP in phospholipid synthesis. (B) UTP in complex carbohydrate synthesis. (C) ATP in energy for the cell. (D) GTP in protein synthesis. (E) TTP in phosphoryl group transfers.

21. In phosphoryl group transfer reactions, the________ of the nucleotide serves as an information symbol, channeling the nucleotide to appropriate metabolic activities. (A) sugar (B) diphosphate anhydride (C) sugar-phosphate ester (D) base (E) none are true

22. All of the following are true for tRNA EXCEPT: (A) each amino acid in proteins has at least one unique tRNA species dedicated to chauffeuring its delivery to ribosomes for insertion into growing polypeptides. (B) are small molecules containing 73-94 residues. (C) fold into characteristic secondary structures. (D) possess a 3'terminal nucleotide sequence that reads -CCA. (E) all are true.

23. DNA double helix structure is stabilized by all of the following EXCEPT: (A) the sugar-phosphate backbones are oriented in opposite directions. (B) the glycosidic bonds holding paired bases are directly across the helix from one another. (C) cations such as Mg2⁺bind to the anionic phosphates. (D) bases stack together through hydrophobic interactions and van der Waals forces. (E) appropriate base pairing builds a polymer whose external dimensions are uniform.

24. Urea and formamide are agents that denature dsDNA by (A) intercalating between base pairs and disrupting van der Waals interactions. (B) forming ionic bonds with the backbone phosphates. (C) competing effectively with the H-bonding between the base pairs. (D) changing the pH to cause hydrolysis. (E) none are true

25. In the Southern hybridization procedure, the gel after electrophoresis is treated with NaOH and then neutralized before blotting. What is the primary function of the alkaline treatment? (A) It neutralizes any acid soluble impurities in the gel. (B) It cleaves the DNA into smaller fragments to permit greater efficiency of transfer. (C) It inactivates any restriction endonucleases that may be in the gel. (D) It neutralizes any acidic phosphate groups that might prevent hybridization. (E) It denatures the duplex DNA to single-stranded DNA (SsDNA).

26. All are true for cDNA libraries EXCEPT: (A) reverse transcriptase synthesizes a DNA strand complement of the mRNA templates. (B) mRNA templates are isolated using oligo (dA)-cellulose chromatography. (C) linkers are added and the cDNA is cloned into suitable vectors. (D) the cDNA are copies from mRNA templates. (E) all are true

27. An enzyme's specificity can be due to: (A) the ratio of catalyzed rate to the uncatalyzed rate of reaction. (B) molecular recognition based on structural complementarity. (C) amount of enzyme produced by the cell. (D) amount of substrate available. (E) metabolic activators.

28. All of the following are properties of a coenzyme EXCEPT: (A) They are usually actively involved in the catalytic reaction of the enzyme. (B) They tend to be stable to heat. (C) They can serve as intermediate carriers of functional groups. (D) They are protein components. (E) They may contain vitamins as part of their structure.

29. All of the following statements about competitive inhibition are correct EXCEPT: (A) Competitive inhibitors are often chemical analogs of the substrate. (B) For a group-specific enzyme, one substrate would be a competitive inhibitor of reactions of the other possible substrate. (C) Sometimes a product of an enzyme-catalyzed reaction is a competitive inhibitor of its own production. (D) In the presence of a competitive inhibitor, the apparent Km would be altered and V max would be decreased. (E) Competitive inhibitors usually interact with the enzyme at the binding site for a substrate.

30. Malonate inhibition of succinate dehydrogenase is an example of: (A) noncompetitive inhibition. (B) competitive inhibition. (C) mixed noncompetitive inhibition. (D) irreversible inhibition. (E) uncompetitive inhibition.

31. All are true for the enzyme-transition state complex EXCEPT: (A) It is designated as . (B) The enzyme stabilizes the transition-state complex more than it stabilizes the substrate complex. (C) The enzyme is "designed" to bind the transition-state structure more tightly than the substrate or product. (D) The energy barrier between ES and is less than the energy barrier between S and . (E) All are true.

32. All are true for low-barrier hydrogen bonds EXCEPT: (A) The hydrogen is centered between the two heteroatoms. (B) The interactions are more covalent. (C) The bond order approaches 0.5 for both O-H interactions. (D) The barrier that the bydrogen atom must surmount to exchange oxygens becomes lower. (E) All are true.

33. The mechanism of chymotrypsin involves which of the following elements? (A) deprotonation of an active site Asp residue by His to start the reaction (B) formation of an acyl-enzyme intermediate that must be hydrolyzed to complete the reaction (C)stabilization of the positively charged His by a Gin residue (D) direct deprotonation of water by His to generate a hydroxide ion for initiation of the reaction (E) both a and b occur

34. HIV-1 protease is different from most mammalian aspartic acid proteases in that it has: (A) two subunits each with a two-aspartate active site. (B) two subunits each contributing an aspartate to the active site. (C) two active sites on one protein. (D) two subunits, one with an active site, and the other with a regulatory activity. (E) none of the above.

35. All are true for cAMP-dependent protein kinase EXCEPT: (A) also known as PKA. (B) phosphorylase kinase is a substrate. (C) consists of a pair of catalytic subunits. (D) two regulatory subunits block catalytic activity without cAMP binding. (E) phosphorylates glycogen phosphorylase.

36. The T form (tense or taut form) of deoxyhemoglobin differs from oxyhemoglobin (the R form or relaxed form) by all EXCEPT: (A) covalent linkages between subunits. (B) specific intrachain hydrogen bonds. (C) between β-subunit salt links (ion-pair bonds). (D) between a-subunits salt links (ion-pair bonds). (E) intrachain salt bridges.

37. What is the relationship between photoautotrophs and heterotrophic cells? (A) Photoautotrophs use light energy for synthesis of organic molecules while heterotrophs metabolize organic substances for fuel and building blocks. (B) photoautotrophs use organic compounds as a source of carbon while heterotrophs use CO₂ as a source of carbon. (C) Photoautotrophs synthesize CO₂ while heterotrophs synthesize O₂. (D) Heterotrophs convert solar energy into chemical energy while photoautotrophs break down organic molecules. (E) There is no relationship between the two.

38._____________ , a pathway that synthesizes glucose from non-carbohydrate precursors, uses seven of the same enzymes as glycolysis, but must replace three enzymes of glycolysis because they are_____________ . (A) Catabolism； to oxidative (B) Gluconeogenesis； irreversible (C) Oxidative phosphorylation； reductive (D) Gluconeogenesis； anabolic (E) Oxidative phosphorylation； irreversible

39. Fructose in the diet or fructose from sucrose in the diet can be a source of calories for fat synthesis in the liver because: (A) ketoses are fattening (B) fructose enters glycolysis after the primary regulation point, PFK-1 (C) fructose provides a net of four ATP from glycolysis (D) fructose enters the branch of glycolysis that forms fat (E) glycerol (the "backbone" of triacylglycerols) comes specifically from fructose

40. Galactosemic individuals can be treated by___________ adults due to metabolism of galactose-1-phosphate by: (A) medication； UDP-glucose pyrophosphorylase. (B) medication； UDP-glucose-4-epimerase. (C) restrictive diet； phosphoglucomutase. (D) restrictive diet； UDP-glucose pyrophosphorylase. (E) all of the above.

41. Isocitrate dehydrogenase has all of the characteristics EXCEPT: (A) ADP raises the Km for isocitrate by a factor of 10. (B) virtually inactive in the absence of ADP. (C) sufficiently exergonic to pull the aconitase reaction forward. (D) allosterically inhibited by NADH and ATP. (E) an oxidative-decarboxylation reaction. and the abnormality may disappear in

42. All are characteristics of succinyl-CoA synthetase EXCEPT: (A)succinyl-CoA can be used to drive phosphorylation of GDP or ADP. (B) the enzyme is named for the reverse reaction. (C) it provides an example of substrate-level phosphorylation. (D) succinyl-phosphate is an intermediate in the reaction catalyzed by succinyl-CoA synthetase. (E) all of the above are true.

43. Does electron transport stop if rotenone is added? Why? (A) Yes, there is not an electron source. (B) No, rotenone is not strong enough to inhibit all of the electron transport chain. (C) No, there is still a source of electrons from Complex II. (D) Yes, rotenone inhibits complex III, therefore, electrons can not be passed on. (E) Can not be determined from the information given.

44. All are properties of glycerol-3-phosphate dehydrogenases EXCEPT: (A) one is located in the cytosol. (B) works to carry electrons into mitochondria. (C) one is located in the inner mitochondrial membrane. (D) mitochondrial enzyme has bound coenzyme Q (E) FAD-dependent mitochondrial enzyme.

45. Which of the following statements about the light reactions of photosynthesis is true? (A) There are two distinct photosystems, linked together by a mechanism similar to electron transport. (B) The source for electrons is located in the stroma of the thylakoid. (C) The Mn complex is the primary electron acceptor and is located on photosystem I. (D) The ultimate electron donor is molecular oxygen. (E) Plastoquinone is a fixed electron transporter in the system located in the inner membrane.

46. When light energy is absorbed by chlorophyll an electron is promoted to a higher orbital and then transferred to a suitable acceptor resulting in light energy conversion to chemical energy in a(n): (A) isomerase reaction. (B) mutase reaction. (C) ligase reaction. (D) oxidation-reduction reaction. (E) none of the above.

47. In the gluconeogenic pathway, the three regulated reactions of glycolysis c and are replaced by_________ ，_________ and_________ are replaced by alternative reactions. (A) glucokinase； PFK-1； pyruvate kinase (B) phosphoglucoisomerase； PFK-1； pyruvate kinase (C) PFK-1； triose phosphate isomerase； pyruvate kinase (D) glucokinase； PFK-1； glyceraldehyde-3-phosphate dehydrogenase (E) glucokinase； PFK-1； pyruvate carboxylase

48. Which of the following is absolutely essential for the activation of pyruvate carboxylase? (A) high concentrations of acetyl-CoA (B) low levels of ATP (C) high levels of oxaloacetate (D) high levels of TCA cycle intermediates (E) high levels of citrate