95年 - 高雄醫學大學招生考試_學士後醫學系:生物化學#113611

1. In Base Excision Repair, the enzyme to act is a_________. (A) gyrase (B) AP endonuclease helicase (C) dam methylase (D) helicase (E) DNA glycosylase

2. Glycogen phosphorylase can be regulated by_________. (A) glycosylation (B) phosphorylation (C) methylation (D) ADP ribosylation (E) acetylation

3. Which one of the following amino acid side chains can be used in acid-base catalysis? (A) Glycine. (B) Histidine. (C) Leucine. (D) Valine. (E) Alanine.

4. Which of the following amino acid residues of a protein is involved in ubiquitinylation? (A) Asparagine. (B) Aspartic acid. (C) Lysine. (D) Arginine. (E) Histidine.

5. For the double-strand break repair of DNA, several proteins are directly involved, such as_______ . (A) cyclins (B) globulin (C) histone protein (D) DNA-dependent protein kinase (E) DNA primase

6. Please estimate the molecular weight (g/mole) of a plasmid DNA of E. coli that contains 3000 base pairs.(A)2.20 x 10⁵(B)7.00 x 10⁵ (C) 1.26 x 10⁶ (D) 1.89 x 10⁶ (E) 2.52 x 10⁶

7. For different IgG molecules, antibody diversity is generated by_____. (A) alternative splicing of the RNA transcripts (B) highly regulated expression of one thousand differently antibody genes (C) post translational modification of antibody genes (D) somatic recombination and somatic mutations of antibody genes (E) intron shuffling of antibody genes

8. Tay-Sachs disease is caused by deficiency of_____. (A) ceramidase (B) sphingomyelinase (C) beta-galactosidase (D) hexaminidase A (E) alpha-fucosidase

9. Which amino acid is the substrate for NO synthetase to form nitric oxide (NO)? (A) Glutamine. (B) Arginine. (C) Asparagine. (D) Histidine. (E) Proline.

10. Cholesterol can act as a precursor for each of the following compounds except_____ . (A) chenodeoxycolic acid (B) 1,25-dihydroxycholecalciferol (C) testosterone (D) glycocholic acid (E) cholecystokinin

11. The p53 gene (tumor suppressor gene) product is_____. (A) a G protein (B) a DNA-binding protein (C) a tyrosine kinase (D) a serine/threonine kinase (E) a GTPase

12. Pyridoxal phosphate is a cofactor for which of the following enzymatic reaction? (A) Fixation of carbon dioxide. (B) Oxidation-reduction. (C) Aminotransferase. (D) Phosphate group transfer. (E) Isomerase.

13. Which of the following enzymes converts stearoyl-CoA to oleoyl-CoA? (A) △ ⁵ desaturase. (B) △ ⁶ desaturase. (C) △ ⁷ desaturase. (D) △⁸ desaturase. (E)△⁹ desaturase.

14. All of the following compounds are intermediates of the Kreb cycle except_______ . (A) isocitrate (B) malate (C) oxaloacetate (D) pyruvate (E) succinate

15. If the numbering of fatty acids in the carboxyl carbon is number 1, which carbon in palmitic acid is oxidized during the first cycle of E-oxidation? (A) 1 (B) 2 (C) 3 (D) 4 (E) 15

16. The following techniques could be potentially employed as a tool in gene therapy except_______ . (A) RNAi (B) Antisense DNA (C) Triplex DNA (D) Ribozyme (E) DNA bending

17. In glycoproteins, the carbohydrate moiety is always attached through the amino acid residues_______. (A) tryptophan, aspartate or cysteine (B) asparagine, serine or threonine (C) glycine, alanine or aspartate (D) aspartate or glutamate (E) glutamine or arginine

18. Sphingosine is not a component of_______. (A) cardiolipin (B) ceramide (C) cerebrosides (D) gangliosides (E) sphingomyelin

19. The ion channel that opens in response to acetylcholine is an example of a ____________ signal transduction system. (A) G protein (B) ligand-gated (C) receptor-enzyme (D) serpentine receptor (E) voltage-gated

20. A monoclonal antibody differs from a polyclonal antibody in that monoclonal antibodies_______. (A) are labeled with chemicals that can be visualized (B) are produced by cells from the same organism that produced the antigen (C) are synthesized by a population of identical, or “cloned” cells (D) are synthesized only in living organisms (E) have only a single polypeptide chain that can recognize an antigen

21. Below is a diagram of two DNA strands that are part of the coding region of gene. What is the sequence of bases and strand orientation in the transcribed RNA molecular?

5’ --- GTACGTGAA---3’ coding strand

3’ --- CATGCACTT---5’ template strand (A) 3’ GUACGUGAA 5’ (B) 5’ GTACGTGAA 3’ (C) 3’ CAUGCACUU 5’ (D) 5’ CAUGCACUU 3’ (E) 5’ GUACGUGAA 3’

22. The human genetic disease phenylketonuria (PKU) can result from_______ . (A) lack of phenylalanine decarboxylase (B) deficiency in aromatic amino acid transaminase (C) a deficiency of protein in the diet (D) overproduction of ketone bodies (E) lack of an enzyme required for converting phenylalanine to tyrosine

23. Which of the following descriptions is not correct? (A) The leucine zipper motif is important for protein-DNA interaction. (B) Ribozymes are RNA molecules with catalytic activity. (C) The poly( A ) tail can stimulate recruitment of the 40s ribosomal subunit to mRNA； therefore, it is important in initiation of protein synthesis. (D) Diphtheria toxin can inhibit mammalian RNA synthesis by reduction the elongation factor-2 activity. (E) The suppressor tRNA molecules are capable of suppressing missense mutations.

24. “The knock-out mice” is an important animal model for biomedical research. One of the most important techniques involving in this transgenic animal’s establishment is_______ . (A) receptor expression in embryonic stem cell (B) gene targeting by homologous recombination (C) gene amplification in embryonic fibroblast cell (D) technique of chromosome walking (E) single nucleotide polymorphism analysis

25. If a sample of DNA is found to have the base composition (molar ratios) of adenine, 40； thymine, 22； guanine, 19 and cytosine, 19, what conclusion can be drawn? (A) The DNA is a circular duplex. (B) The DNA is a linear duplex. (C) The DNA is single stranded. (D) The DNA has highly repetitive sequences. (E) The DNA has a high melting temperature.

26. Which of the following statements concerning cyclins is not correct? (A) They catalyze the phosphorylation of cyclin-dependent protein kinases. (B) They are regulatory subunits for enzymes that catalyze the phosphorylation of proteins. (C) They are activated and degraded during the cell cycle. (D) They can become linked to ubiquitin. (E) They contain specific amino acid sequences that target them for proteolysis.

27. That the nature of genetic material is DNA is based on_______ . (A) the transforming material is heat-unstable (B) DNase digestion has no effects but RNase digestion can destroy the activity (C) the base composition of DNA is constant from one species to another (D) only DNA can enter the cell if E. coli is infected by T2 phage (E) UV absorption maximum is at 280 nm

28. Which one of the following statements relating to the common amino acids is correct? (A) Glutamine and asparagine have acidic side chains. (B) Valine and leucine have polar side chains containing an amide group. (C) Only phenylalanine and tyrosine absorb in the ultraviolet region near 270 nm. (D) There are three amino acids whose side chains carry a net positive charge at pH 5. (E) Methionine is one of three sulfur containing amino acids.

29. Which one of the following statements relating to lipids and membrane is correct? (A) The non-polar interior of a lipid bilayer relies on salt bridges for its stability. (B) Triacylglycerols are the simplest of the phospholipids. (C) Cholesterol molecules are generally used to provide ion channels. (D) The ability of species to migrate through a lipid bilayer increases with their polarity. (E) Unsaturated fatty acyl groups used in phospholipids are normally cis isomers.

30. In a tissue that metabolizes glucose via the pentose phosphate pathway, carbon number 1 of glucose would be expected to end up principally in_______ . (A) glycogen (B) 3-phosphoglycerate (C) carbon dioxide (D) ribose-5-phosphate (E) pyruvate

31. Which one of the following statements relating to proteins is correct? (A) All proteins have quaternary structure. (B) Histidine is often found at the active site of globular proteins. (C) The primary structure of a protein describes the amino acid composition, but not the amino acid sequence. (D) Both alpha-helix and beta-sheet segments occur as secondary structural elements in all proteins. (E) When proteins are denatured, they can never be reconstituted back to a functional state.

32. The Type II glycogen disease (Pompe’s disease) is lack of _______. (A) glucose-6-phosphatase (B) glucose-1-phosphatase (C) lysosomal alpha-1 to 4- and 1 to 6- glucosidase (acid maltase) (D) debranching enzyme (E) branching enzyme

33. Severe combined immunodeficiency disease (SCID) is caused by deficiency of_______ . (A) adenosine deaminase (B) thymidine kinase (C) xanthine oxidase (D) DNA ligase (E) hypoxanthine-guanine phosphoribosyltransferase

34. Which one of the following statements about natural fatty acids is correct? (A) Molecules with odd and even numbers of carbon atoms are equally common. (B) All of the natural fatty acids are unsaturated. (C) Fatty acids provide a useful source of intermediates for gluconeogenesis. (D) Oxidation of fatty acids can lead to the production of ketone bodies. (E) The natural unsaturated fatty acids most commonly have their double bonds in trans geometry.

35. Which one of the following statements relating to lipids and membranes is correct? (A) Triacylglycerols are the major component of most cell membranes. (B) Clusters of cholesterol molecules are generally used to provide ion channels. (C) Na⁺ and K⁺ ions readily diffuse through the lipid bilayer. (D) Both saturated and unsaturated fatty acyl groups are used in typical phospholipids. (E) All phospholipids incorporate a glycerol unit as part of their structure.

36. Which one of the following statements about cholesterol is correct? (A) The complete oxidation of cholesterol to CO₂ and H₂O occurs in the liver as an energy source. (B) Cholesterol esters are an important component of the outer monolayer of lipoproteins. (C) Some cholesterol synthesis occurs in the liver but most takes place in other tissues. (D) Beta-hydroxy-beta-methylglutaryl-CoA is generated from three molecules of acetyl-CoA and is an intermediate in cholesterol biosynthesis. (E) Cholesterol is an important precursor for the production of the various prostaglandins, important in a broad range of physiological roles.

37. Which of the following enzymes in liver is/are activated as a result of an elevated insulin level after a meal? (A) cAMP-dependent protein kinase and adenylate cyclase (B) Fructose 1,6 bisphosphate (FBPase-1) (C) Glycogen phosphorylase, phosphokinase (D) Glycogen synthase, phosphofructo-kinase-1 (PFK-1), and pyruvate kinase (E) Phosphoenolpyruvate carboxykinase (PEPCK)

38. Oncogenes that have tyrosine kinase activity_______ . (A) probably correspond to protooncogenes that are growth factor receptors (B) probably correspond to protooncogenes that are polypeptide growth factors (C) are probably Gs proteins (D) are probably Gi proteins (E) are probably DNA binding proteins

39. Correct statements regarding arachidonic acid include all of the following except_______ . (A) it is a precursor of thromboxane A₂ (B) it activates lipoxygenase (C) it is a 20-carbon fatty acid with three double bonds (D) it can be derived from linoleic acid (E) it is esterified to the sn-2 position of glycerophospholipids

40. The cost in high-energy phosphate bonds for the formation of 1 mol of glucose from lactate is_______ . (A) 8 mol of ATP (B) 6 mol of ATP (C) 4 mol of ATP (D) 2 mol of ATP (E) none of the above

41. In the sequence of reactions that convert lactate to glucose in cells capable of gluconeogenesis, three reactions are used to bypass enzymes of the glycolytic pathway in which glucose is converted to lactate. All of the following enzymes fall into this category except_______ . (A) pyruvate carboxylase (B) pyruvate dehydrogenase (C) phosohoenolpyruvate carboxykinase (D) fructose 1,6-diphosphatase (E) glucose 6-phosphatase

42. Carbon monoxide inhibits mitochondria electron transport by_______ . (A) binding to hemoglobin in the erythrocytes and so blocking the transport of oxygen to tissues (B) binding to the oxygen-binding site of cytochrome oxidase (C) blocking electron transport at the level of the cytochrome b-cytochrome c₁ complex (complex III) (D) combining with coenzyme Q and preventing its interaction with nonheme iron-surfur-protein center of complex II (E) inhibiting the electron transfer of complex I

43. If the substrate concentration in an enzyme catalyzed reaction is equal to 0.5 Km, the initial reaction velocity will be _______. (A) 0.25 Vmax (B) 0.33 Vmax (C) 0.50 Vmax (D) 0.67 Vmax (E) 0.75 Vmax

44. An enzyme that catalyzes the conversion of an aldose sugar to a ketose sugar would be classified as one of the_______. (A) oxidoreductases (B) transferases (C) hydrolases (D) isomerases (E) lyases

45. An analysis of chromosomal DNA, using the Southern blot technique, involves the following five major steps: ①Autoradiography； ②Blotting； ③ Cleavage；④Electrophoresis； ⑤Hybridization；
Which of the following sequences of steps best illustrates this technique? (A)①②③④⑤ (B) ①③②④⑤ (C) ③⑤②④①(D) ③②⑤④①(E) ③④②⑤①

46. The two nitrogen atoms in urea arise from______. (A) ammonia and glutamine (B) glutamine and aspartic acid (C) glutamine and glutamic acid (D) glutamic acid and alanine (E) ammonia and aspartic acid

47. Which of the following statements about antibiotic inhibitors of protein synthesis is correct? (A) Chloamphenicol inhibits the peptidyl transferase activity of the large ribosomal subunit in eukaryotes. (B) Cycloheximide inhibits the peptidyl transferase activity of the large ribosomal subunit in eukaryotes. (C) Puromycin blocks protein synthesis in prokaryotes only. (D) Streptomycin inhibits protein synthesis by binding to 30S ribosomal subunits. (E) Erythromycin inhibits translocation in eukaryotes only.

48. A biochemist is attempting to separate a protein X from protein C in a solution. The proteins have the following properties:

What type of protein separation techniques might be the best one to separate protein X from protein C? (A) Gel filtration (B) SDS-polyacrylamide gel electrophoresis (C) Affinity chromatography (D) Ion-exchanger chromatography (E) Agarose gel electrophoresis

49. A sequence of amino acids in a certain protein is found to be –Ser–Gly–Pro–Gly–. The sequence is most probably part of a(n)______. (A) β-turn (B) parallel β-sheet (C) α-helix (D) α-sheet (E) antiparallel β-sheet

50. Which of the following is (are) true of the oxidation of 1 mol of palmitate (a 16-carbon saturated fatty acid； 16:0) by the β-oxidation pathway, beginning with the free fatty acid in the cytoplasm?
①Activation of the free fatty acid requires the equivalent of two ATPs.
② Inorganic pyrophosphate (PPi) is produced.
③Carnitine functions as an electron acceptor.
④8 mol of FADH₂are formed.
⑤8 mol of acetyl-CoA are formed.
⑥There is no direct involvement of NAD+ . (A)①and⑤ (B) ①②and⑤(C) ①② and⑥ (D) ①③ and ⑤ (E)④ and⑤

51. Which of the following peptides is more likely to be nuclear targeting signal? (A) ser-ser-thr-asn-arg-lys-met-thr (B) arg-lys-lys-arg-arg-lys-leu-met (C) met-leu-ile-phe-leu-met-ile-ile (D) ser-ser-thr-thr-thr-thr-ser-thr-ser (E) asn-lys-ser-asn-lys-ser-asn-lys-ser

52. Myoglobin and the subunits of hemoglobin have______ . (A) no obvious structural relationship (B) very different primary and tertiary structures (C) very similar primary and tertiary structures (D) very similar primary structures, but different tertiary structures (E) very similar tertiary structures, but different primary structures

53. Which one of the following analytical techniques does not help illuminate a gene’s cellular function? (A) Southern blotting (B) DNA microarray analysis (C) Protein chip analysis (D)Two-dimensional gel electrophoresis (E) Two-hybrid analysis

54. Hormone-activated phospholipase C can convert phosphatidylinositol 4,5-bisphosphate to______ . (A) diacylglycerol + inositol triphosphate (B) diacylglycerol + inositol+ phosphate (C) glycerol + inositol + phosphate (D) glycerol + phosphoserine (E) phosphatidyl glycerol + inositol + phosphate

55. Oxidative phosphorylation and photophosphorylation share all of the following except______ . (A) chlorophyll (B) involvement of cytochromes (C) participation of quinones (D) proton pumping across a membrane to create electrochemical potential (E) use of iron-sulfur proteins

56. A certain bacterial mRNA is known to represent only one gene and to contain about 800 nucleotides. If you assume that the average amino acid residue contributes 110 to the peptide molecular weight, the largest polypeptide that this mRNA could code for would have a molecular weight of about ______ . (A) 800 (B) 30,000 (C) 5,000 (D) 80,000 (E) An upper limit cannot be determined from the data given

57. Which of the following statements about the polymerase chain reaction (PCR) is false? (A) DNA amplified by PCR can be cloned. (B) DNA is amplified at many points within a cellular genome. (C) Newly synthesized DNA must be heat-denatured before the next round of DNA synthesis begins. (D) The boundaries of the amplified DNA segment are determined by the synthetic oligonucleotides used to prime DNA synthesis. (E) The technique is sufficiently sensitive that DNA sequences can be amplified from a single animal or human hair.

58. Which of the following is not true of the citric acid cycle? (A) All enzymes of the cycle are located in the cytoplasm, except succinate dehydrogenase, which is bound to the inner mitochondrial membrane. (B) In the presence of malonate, one would expect succinate to accumulate. (C) Oxaloacetate is used as a substrate but is not consumed in the cycle. (D) Succinate dehydrogenase channels electrons directly into the electron transfer chain. (E) The condensing enzyme is subject to allosteric regulation by ATP and NADH.

59. Steroid receptor proteins are a class of closely-related DNA binding proteins. These steroid receptor proteins contain tandem DNA binding motifs called______ . (A) zinc fingers (B) homeodomains (C) leucine zippers (D) helix-turn-helix motifs (E) helix-loop-helix motifs

60. Which of the following sequences is most likely to contain a termination signal for procaryotic RNA polymerase? (A) 5’-GUGCGGCGAUUCAUCGCCGCUUUUUAGCUCCUAGC-3’ (B) 5’-GUGCGGCGAUUCAUCGCCGCAGCUCCUAGCUUUUU-3’ (C) 5’-AUUCAUGUGCGGCGCGCCGCAGCUCCUAGCUUUUU-3’ (D) 5’-GUGCGGCGAUUCAUCGCCGCAAUAAAGGGGGCCCC-3’ (E) 5’-AAAAAUUUUUUAAUAAAAGGGGGGGGUUUUUUGG-3’

95年 - 高雄醫學大學招生考試_學士後醫學系:生物化學#113611

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