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BLUEPRINT OF THE CORE TOPICS IN BIOCHEMISTRY PROTEIN AND AMINO ACID CHEMISTRY I. AMINO ACIDS - General structure of an L--amino acid - Classification of the 20 naturally occurring L--amino acids - Functions of amino acids - Physical and chemical properties of amino acids - Formation of the peptide bond II. PROTEINS - Functions of proteins - Classification based on composition, shape and function - 4 levels of structural organization – primary, secondary, tertiary and quaternary - Changes brought about by denaturation of proteins - Steps in protein analysis - General principles behind the use of chromatography and electrophoresis in the separation, purification and identification of proteins and amino acids MULTIPLE CHOICE QUESTIONS _B__1. This is an uncharged, polar amino acid: A. Valine B. Cysteine C. Alanine D. Aspartic acid _A__2. The naturally occurring tranquilizer of the body is derived from this amino acid: A. Glutamic acid B. Glycine C. Histidine D. Arginine _C__3. At its isoelectric point, an amino acid is: A. fully protonated B. fully ionized C. uncharged D. a good buffer _B__4. The secondary level of protein structure is maintained by: A. Peptide bonds between amino acid residues B. Hydrogen bonds between peptide bonds C. Hydrogen bonds between R groups of amino acids D. all of the above _C__5. The most visible effect of denaturation on proteins is: A. decreased levorotation C. decreased solubility B. increased digestibility D. loss of biologic function _D__6. This reaction is used to determine the N-terminal amino acid in a peptide chain: A. Reaction with lithium borohydride C. Hydrazinolysis B. Reaction with cyanogen bromide D. Reaction with danzyl chloride _A__7. The basis of separation of amino acids subjected to paper chromatography: A. differences in solubility C. differences in charge B. differences in size D. differences in polarity I. II. III. IV. V. VI. VII. VIII. PROTEIN AND AMINO ACID METABOLISM Digestion of dietary proteins Mechanisms of absorption of amino acids Central role of the liver in protein and amino acid metabolism Essential vs non-essential amino acids – nutritional differences Complete vs incomplete protein Ways of catabolizing an amino acid A. oxidative deamination D. decarboxylation B. non-oxidative deamination E. oxygenation C. transamination F. one-carbon transfer Biochemical mechanisms by which the body handles or detoxifies ammonia A. Reversed glutamate dehydrogenase reaction B. Glutamine formation C. Urea formation – Urea cycle - Rate-limiting steps and enzymes - Control steps - Inborn errors related to urea synthesis D. Asparagine formation Ammonia intoxication - causes - metabolic pathways affected - mechanism behind the occurrence of coma in severe liver disease - principle behind the management of ammonia intoxication Metabolic fates of the carbon skeletons of amino acids - glucogenic amino acids - ketogenic amino acids IX. X. Miscellaneous catabolic pathways of each amino acid - important substances derived from each amino acid - inborn errors of metabolism related to each amino acid Nitrogen balance - Physiological or disease states which lead to + or negative nitrogen balance - Metabolic processes which contribute to the maintenance of nitrogen balance QUESTIONS on PROTEIN and AMINO ACID METABOLISM _B__8. This could be a limiting amino acid in an incomplete protein: A. Glutamic acid B. tryptophan C. asparagine D. Serine _A__9. The most active enzyme involved in oxidative deamination: A. Glutamate dehydrogenase C. glutaminase B. glutamine synthetase D. L-amino acid oxidase _C__10. This amino acid does not undergo transamination: A. Valine B. Glutamine C. Lysine D. Arginine _D__11. Major means by which the brain detoxifies ammonia: A. Urea formation C. asparagine formation B. reversed glutamate dehydrogenase reaction D. glutamine formation _A__12. This enzyme of the urea cycle requires N-acetylglutamate as positive modulator: A. carbamoyl phosphate synthetase C. Ornithine transcarbamylase B. argininosuccinase D. arginase _C__13. The immediate cause of coma occurring in severe liver disease is the depletion of this substance in the cell: A. glutamine B. glutamic acid C. -ketoglutarate D. oxaloacetate _B__14. This amino acid is both glucogenic and ketogenic: A. Phenylalanine B. Valine C. Histidine D. Arginine _D__15. Cause(s) of PKU: A. Deficiency of phenylalanine monooxygenase C. deficiency of NADPH B. deficiency of dihydrobiopterin reductase D. all of the above _A__16. This inborn error related to methionine metabolism is manifested by skeletal deformities and dislocation of the lens of the eyes: A. Homocystinuria B. Cystinosis C. Cystathioninuria D. Cystinuria _C__17. All of the following conditions are characterized by negative nitrogen balance, EXCEPT: A. prolonged illness C. convalescence B. metabolic stress D. intake of poor quality protein LIPID CHEMISTRY A General structure of the different types of lipid B. Classification of the different lipids C. Functions D. Physical and chemical properties Questions on Lipid chemistry _D__18. Structural characteristics of cardiolipin: A. one glycerol, two fatty acids and phosphoric acid B. three glycerol, two phosphoric acid and 3 fatty acids C. two glycerol, two phosphoric acid and 4 fatty acids D. three glycerol, two phosphoric acid and 4 fatty acids _B__19. Which form of lipid acts as storage form of energy? A. phospholipids C. cholesterol B. triacylglycerides D. sphingolipids _A__20. Which among the lipoproteins is responsible for exogenous transport of triglycerides? A. chylomicrons C. Low density lipoproteins B. Very low density lipoproteins D. High density lipoproteins _B__21. Which among the eicosanoids can promote platelet aggregation? A. prostacyclin C. Leukotrienes B. thromboxane D. Prostaglandins _A__22. Lipid that acts as surfactant and deficient in cases of Respiratory Distress syndrome: A. lecithin B. cephalin C. cardiolipin D. lysolecithin Lipid Metabolism Blueprint and Questions I. Fatty acid synthesis (lipogenesis) _B__ 23. Which of the following is the end-product of extramitochondrial lipogenesis? A. oleic acid C. palmitoleic acid B. palmitic acid D. stearic acid _D__ 24. The rate-limiting step in the de novo synthesis of fatty acid is the formation of: A. acetyl CoA C. butyryl CoA B. acetoacetyl CoA D. malonyl CoA II. Beta oxidation of fatty acid _A__ 25. Thiolytic cleavage of two carbon atoms from the fatty acid results in the release of: A. acetyl CoA B. succinyl CoA C. propionyl CoA D. malonyl CoA _C__ 26. Which of the following is the committed step in beta oxidation? A. activation of fatty acid C. carnitine transport B. oxidative step D. ketothiolysis III. Cholesterol biosynthesis _C__ 27. Which of these enzymes catalyze the rate-limiting step in cholesterol synthesis? A. HMG-CoA synthase C. HMG-CoA reductase B. HMG-CoA oxidase D. HMG-CoA acetylase _B__ 28. The most expensive stage in the biosynthesis of cholesterol is the formation of: A. mevalonate C. squalene B. isopentenyl pyrophosphate D. lanosterol IV. Lipoprotein metabolism _D__ 29. Which of the following lipoproteins transport dietary lipids in the blood? A. HDL B. VLDL C. LDL D. chylomicron _A__ 30. The reverse transport of cholesterol in the blood is the function of: A. alpha lipoprotein C. prebeta lipoprotein B. beta lipoprotein D. intermediate density lipoprotein V. Lipolysis _A__ 31. Which of the following hormones is antilipolytic? A. insulin B. thyroxine C. epinephrine D. glucagon _C__ 32. Which one is the major regulatory enzyme in lipolysis? A. lipoprotein lipase C. hormone-sensitive lipase B. pancreatic lipase D. hepatic lipase VI. Triacylglycerol synthesis _B__ 33. In the adipose tissue, the source of glycerol 3-phosphate for triglyceride synthesis is obtained from this glycolytic intermediate. A. glucose 6-phosphate C. 1,3 bisphosphoglycerate B. dihydroxyacetone phosphate D. glyceraldehyde 3-phosphate VII. Ketogenesis _D__ 34. Which of the following ketone bodies is synthesized by the action of HMG-CoA lyase? A. acetone C. pyruvic acid B. beta-hydroxybutyric acid D. acetoacetic acid VIII. Phospholipid metabolism _A__ 35. The action of phospholipase C results in the: A. formation of second messengers of hormones B. release of arachidonic acid C. synthesis of lysophospholipid D. release of long-chain saturated fatty acid IX. Sphingolipid metabolism _C__ 36. All sphingolipids are synthesized from which of the following precursors? A. glycerol B. phosphatidic C. ceramide D. cholesterol X. Eicosanoid metabolism _B__ 37. All of the following are products of the action of cyclooxygenase, EXCEPT: A. prostaglandin B. leukotriene C. thromboxane D. prostacyclin ENZYME CHEMISTRY I. Mechanism of action _A__ 38. Enzymes accelerate chemical reactions by: A. lowering the energy of activation of the reactants B. increasing the temperature of the medium C. altering the pH of the reaction D. changing the equilibrium constant of the reaction II. Coenzymes _C__ 39. Which of the following coenzymes is important in carboxylation reaction? A. pyridoxal phosphate B. tetrahydrofolic acid C. biotin D. cobalamin III. Enzyme inhibition _D__ 40. Which type of inhibitor increases the Km but does not affect the Vmax of the reaction? A. irreversible B. noncompetitive C. uncompetitive D. competitive IV. Classification _B__ 41. Digestive enzymes are classified as: A. oxidoreductases B. hydrolases C. isomerases D. transferases V. Clinical application of enzymes _A__ 42. Inhibition of this enzyme by nucleoside analogs is one of the therapeutic regimens of AIDS. A. reverse transcriptase C. restriction endonuclease B. protease D. primase I. II. III. IV. V. CARBOHYDRATE CHEMISTRY General structure of the common sugars Classification of carbohydrates Physical and chemical properties of carbohydrates Distribution and functions of carbohydrates Importance of carbohydrates in nutrition, medicine and dentistry QUESTIONS FOR CARBOHYDRATE CHEMISTRY _A__43. What is responsible for the gram negativity or gram positivity of the bacterial cell wall? A. Peptidoglycan layer C. Dermatan sulfate B. Sialoglycoprotein layer D. Keratan sulfate _C__44. True regarding glycosylation of hemoglobin: A. It is enzymatic B. It affects hemoglobin function C. It will increase crosslinks between protein and nucleic acids if sugar is transferred from hemoglobin to the tissues D. all of the above _C__45. A carbohydrate with antiviral function: A. Inulin C. Arabinoxylane B. Hyaluronic acid D. Sialoglycoprotein I. II. III. IV. CARBOHYDRATE METABOLISM Digestion of carbohydrates Mechanisms of absorption of carbohydrates Utilization of carbohydrates - Glycogenesis and Glycogenolysis - Gluconeogenesis - Glycolysis - Oxidative decarboxylation of pyruvate to acetyl CoA - Oxidation of acetyl CoA in the Kreb’s citric acid cycle - ATP generation by direct substrate phosphorylation - ATP generation by oxidative phosphorylation via the Electron Transport chain - Pentose phosphate pathway Regulation of blood sugar level – organs, hormones and pathways involved QUESTIONS ON CARBOHYDRATE METABOLISM _D__46. Increases in all of the following constitute positive signals for glycogen breakdown EXCEPT: A. calcium ions C. epinephrine B. cyclic AMP D. blood glucose _C__47. Muscle glycogen cannot contribute directly to blood glucose level because: A. Muscle does not have the enzyme glucokinase B. Muscle does not contain glycogen phosphorylase C. Muscle lacks glucose-6-phosphatase D. Muscle lacks the debranching enzyme _B__48. Net ATP molecules generated in the oxidation of one glucosyl residue in glycogen to two moles of lactate in an exercising muscle: A. four B. three C. two D. one _C__49. Anoxic skeletal muscle derives energy from: A. Kreb’s citric acid cycle C. Embden-Meyerhof pathway of glycolysis B. Pentose phosphate pathway D. Oxidation of fatty acids _C__50. Acetyl CoA for extramitochondrial palmitate synthesis is derived from this Kreb’s citric acid cycle intermediate: A. malate C. citrate B. succinate D. alpha-ketoglutarate _D__51. The following are true of fructose-2,6-bisphosphate, EXCEPT: A. It is formed at a rapid rate in the fed state B. It is synthesized by phosphofructokinase-2 C. Insulin increases its rate of synthesis D. It stimulates fructose-1,6-bisphosphatase _B__52. Phosphoenolpyruvate carboxykinase is a regulatory enzyme utilized in: A. Glycogenesis C. Glycogenolysis B. Gluconeogenesis D. Pentose phosphate pathway _A__53. The carbon skeletons of the following amino acids enter Kreb’s citric acid cycle via alpha-ketoglutarate for gluconeogenic conversion, EXCEPT: A. Alanine B. Arginine C. Glutamate D. Histidine _D__54. ATP molecules generated from the oxidation of one citrate molecule to succinate: A. one B. three C. five D. seven _A__55. The organ most vulnerable to hypoglycemia because of its utter dependence on circulating blood glucose for energy: A. Brain B. liver C. kidney D. skeletal muscle NUCLEIC ACID CHEMISTRY and METABOLISM I. Central dogma of molecular genetics (Replication, transcription, translation) II. Covalent structure of nucleotides III. DNA- the genetic material in eukaryotic systems IV. Mutations: alterations in the primary structure of DNAs V. De-novo biosynthesis of purine and pyrimidine nucleotides VI. Salvage pathways for nucleotide biosynthesis VII. Catabolism of purine nucleotides VIII.Drugs affecting purine and pyrimidine metabolic pathways that are used for cancer chemotherapy IX. Diseases associated with purine and pyrimidine metabolism QUESTIONS ON NUCLEIC ACID CHEMISTRY & METABOLISM _B__56. The process of producing DNA from a molecule of RNA: A. replication C. translation B. Reverse transcription D. conjugation _B__57. This DNA form is seen in physiologic conditions where the cell is well hydrated: A. A form B. B form C. Z form D. D form _C__58. Regions of the DNA strand that are easily denatured are rich in this base pair: A. GC B. AT C. AU D. CT _D__59. This is the primary function of nucleic acids: A. source of energy C. regulate hormone functions B. transport molecules D. preservation and transfer of genetic material _B__60. Complete hydrolysis of RNA nucleotides will yield this product, EXCEPT: A. phosphate C. adenine B. deoxyribose D. uracil _D__61. This type of mutation will result to a frame-shift mutation: A. substitution C. transversion B. transition D. insertion and deletion _D__62. The molecular basis of the disease Xeroderma Pigmentosum appears to be: A. rapid water loss caused by defects in the skin’s cell membrane permeability B. inactivation of temperature sensitive transport enzyme system by sunlight C. induction of a virulent provirus upon UV exposure D. a defect in an excision-repair system that removes thymine dimers in DNA _A__63. True regarding salvage pathways of nucleotide metabolism: A. They utilize free bases as substrates for nucleotide biosynthesis B. They take place only in the ribosomes C. They derive the ring from amphibolic sources D. They are more efficient than de novo pathway _C__64. The enzyme that catalyzes the committed step in purine de novo pathway: A. xanthine oxidase C. PRPP glutamyl amido transferase B. PRPP synthetase D. HGPRTase _D__65. Xanthine oxidase inhibitor: A. azaserine C. trimethoprim B. sulfonamides D. allopurinol ENERGY METABOLISM I. Bioenergetics A. Laws of Thermodynamics – definition and derivation B. Chemical reactions of thermodynamic concepts – enthalpy, entropy, Free energy C. ATP and other organophosphates – structure, sources, synthesis and hydrolysis II. Biologic Oxidation A. oxidation-reduction reactions B. Standard redox potential III. Electron transport chain and oxidative phosphorylation A. Functions, components and complexes B. Electron carriers, reducing equivalents and shuttle systems C. Hypothesis and theories in oxidative phosphorylation D. Inhibitors of the ETC V. Oxidative stress – reactive oxygen species, antioxidant enzyme systems VI. Photosynthesis QUESTIONS ON ENERGY METABOLISM _D__66. The first law of thermodynamics may be stated as: A. Energy cannot be transformed from one form to another B. In any spontaneous process the entropy of the universe is maximal C. ∆E = Q + W D. Change in total energy is equal to the amount of heat absorbed by the system less the work done by the system _B__67. This condition shows a decrease in entropy: A. evaporation of water B. growth of organism C. burning of wood D. melting of ice _A__68. Which of the following is an energy-requiring process? A. synthesis of ATP C. hydrolysis of ATP B. muscle contraction D. nerve conduction _D__69. The resulting reducing equivalent from the oxidation of cytosolic NADH in the liver cells will enter the electron transport chain at this complex: A. cyt bc1 C. succinate dehydrogenase complex B. cyt aa3 D. NADH dehydrogenase complex _D__70. True of “binding-change” mechanism of ATP synthesis: A. conformational change of the headpiece of the phosphorylating complex results from the entry of four H+ releasing a mole of ATP B. three H+ are needed to activate ATP synthase to form ATP from ADP and Pi C. release of ATP is energy requiring D. synthesis of ATP is energy requiring _A__71. The major enzymatic defenses against oxidative stress may be provided by this Zn-Cu or Mn-containing enzyme which catalyzes the formation of H2O2 and O2 from superoxide radicals: A. superoxide dismutase C. glutathione peroxidase B. catalase D. glutathione reductase THE HUMAN GENOME AND BASIC MOLECULAR GENETICS I. Information Copying: Replication - Information metabolism - Overview of replication - DNA Polymerases - Other replication proteins - Mechanics and steps of replication - Fidelity of DNA replication II. Information Readout: Transcription - Mechanism of transcription – initiation, elongation, punctuation - Enzymology of RNA synthesis – RNA polymerase - Posttranscriptional processing III. Information Decoding: Translation - Features of the genetic code - Major participants in translation - Mechanism, rates and energetics of translation - Final stages in protein synthesis - Regulation of protein synthesis in prokaryotes IV. Eukaryotic Genes and their expression - The eukaryotic genome - Physical organization of eukaryotic DNA - Cell cycle and DNA replication in eukaryotes - Transcription and its control in eukaryotic cells - Processing of eukaryotic mRNA - Translation in eukaryotes – control, inhibitors and comparison with prokaryotes - Protein targeting in eukaryotes QUESTIONS ON HUMAN GENOME & BASIC MOLECULAR GENETICS __C_72. Mutation in mRNA brought about by transcriptional misreading is not critical in the cell’s survival because: A. RNA polymerase II has 3’-5’ exonuclease activity and can proofread its work B. DNA polymerase II has 3’-5’ exonuclease activity and can proofread its work C. mRNA half-life is short and mRNA is not passed on to the cell’s progeny D. Ribosomes can bypass errors in mRNA transcript and continue with translation _A__73. DNA polymerase can initiate replication only if this protein has laid down molecules which provide 3’-OH attachment for incoming deoxynucleotides: A. DNA-dependent RNA polymerase C. Dna A B. SSB D. Helicase _B__74. What is the most appropriate repair mechanism if both strands of a bacterial DNA are extensively damaged? A. Single-strand excision repair by specific glycosylase B. Recombination with undamaged homologous chromosome C. Repair carried out by 3’-5’ exonuclease activity of DNA polymerase III D. No repair needed, the bacterial cell activates its apoptotic machinery _B__75. Which is not true regarding DNA/RNA/protein synthesis direction? A. DNA and RNA are both synthesized in 5’ to 3’ direction B. The 5’ phosphate of the nascent nucleotide is the target of incoming dNTP C. The 5’ end of incoming nucleotide bears the triphosphate D. Protein synthesis proceeds in the 5’ to 3’ direction _D__76. Which is true regarding start and stop codons? A. Start of transcription is at AUG C. AUG codes for formyl-methionine in humans B. Stop of transcription is at UGA D. Transcription does not terminate at UAA _D__77. What is the most likely scenario in case of promoter mutation? A. mRNA transcript is longer C. protein product is truncated B. Frame-shift mutation D. dramatic decrease in amount of gene transcribed I. II. III. IV. MOLECULAR BASIS OF ONCOGENESIS Cancer – Definition, Basic characteristics, comparison with normal cells Molecular carcinogenesis - Oncogene – classification and mechanism of oncogene activation - Tumor suppressor genes – classification, functions, mechanism of mutation - Mutator genes or DNA repair genes – classification, functions and mechanism of mutation Carcinogen metabolism- classification of carcinogens, mechanisms of chemical, physical and viral carcinogenesis Principal pathways of malignancy QUESTIONS ON ONCOGENESIS _D__78. True statements about oncogenes, EXCEPT: A. They positively affect cell proliferation B. Single mutant allele is enough to cause phenotypic abnormality C. They are mutant proto-oncogenes D. Mutation involves a loss in function _C__79. This is not a characteristic of cancer: A. loss of contact inhibition C. gain in function of mutator gene B. uncontrolled proliferation D. loss of differentiated function _B__80. True statements about RAS oncogene activation, EXCEPT: A. It involves a point mutation in codon 12 B. The mutated RAS results to increased GTPase activity C. The mutated gene codes for valine instead of glycine D. It is over-expressed in bladder cancer _B__81. Stage of chemical carcinogenesis which is epigenetic and reversible: A. initiation C. progression B. promotion D. all of the above METABOLISM OF HORMONES I. Definition, functions, characteristics of hormones in general II. Classification of hormones according to structure and mechanism of action III. Hormone action - Steps in eliciting response of target cells - Receptors - Signal transduction IV. Metabolically active hormones – Insulin, Glucagon, Epinephrine, Cortisol, Thyroid Hormone, Growth hormone, hormones that affect calcium metabolism - synthesis and regulation of secretion - metabolic effects and mechanism of action - Related pathophysiologic conditions QUESTIONS ON HORMONE METABOLISM _C__82. Thyroid hormone upon reaching its target cell will bind to its: A. cell surface receptor C. nuclear receptor B. cytoplasmic receptor D. associated protein _A__83. Activated hormone receptor complex: A. binds to a hormone response unit in the DNA B. always couples with G-protein attached to the cell membrane C. produces first messengers D. directly results to changes in intracellular processes _B__84. This protein substance mediates the growth-related actions of growth hormone: A. insulin B. IGF-I C. somatostatin D. GHRH _C__85. True regarding insulin action on the following enzymes: A. activation of glycogen synthase a by dephosphorylating it B. phosphorylation of hormone sensitive lipase C. increasing activity of phosphofructokinase by dephosphorylating it D. phosphorylates phosphorylase b E. all of the above _D__86. Cortisol ensures the activity of this enzyme forming epinephrine: A. tyrosine hydroxylase C. dopa decarboxylase B. dopamine B-hydroxylase D. PNMT FUNDAMENTALS OF NUTRITION I. Definition of terms - Nutrition - Recommended dietary allowance - Health - Nutrient - Minimum daily requirement - Malnutrition - Nutriture - Food II. Assessment of nutritional status – methods involved based on: - Gomez classification - Waterlow classification - Body mass index III. Different forms of malnutrition IV. 4-4-9 Rule in converting grams of macronutrients to energy equivalent V. Calculation of total caloric requirements of a normal healthy adult VI. Basic components of energy expenditure - Basal metabolic rate - Physical activity - Specific dynamic action of food - Growth VII. Carbohydrates, fats and proteins - Food sources, RDA, Metabolic functions VIII. Breast milk – chemical composition, importance of breastfeeding, comparison with cow’s milk QUESTIONS ON FUNDAMENTALS OF NUTRITION _C__87. True regarding basal metabolic rate: A. increased during starvation C. increased during pregnancy B. increased in hypothyroidism D. increased in old age _B__88. Manifestation(s) of marasmus: A. edema C. hepatomegaly B. skin and bones appearance D. flag sign _B__89. Function(s) of lipids: A. main source of energy B. maintains integrity of cell membrane C. maintains normal osmotic relations among cellular compartments D. build and repair tissues E. all of the above VITAMINS 1. Differences between fat-soluble and water-soluble vitamins 2. General characteristics of each vitamin with emphasis on: - structural, physical and chemical characteristics - active form/coenzyme form of the vitamin - general functions/physiologic roles in body metabolism - transport and storage in the body - biological occurrence or food sources - daily requirements - toxicity manifestations, if any 3. Diseases associated with each vitamin deficiency 4. Correlation of the clinical manifestations of the disease with the physiologic and biochemical functions of the vitamin QUESTIONS ON VITAMINS _B__90. The active part of riboflavin that participates in oxidation/reduction reactions: A. adenine C. phosphoric acid B. isoalloxazine ring D. isopentenyl ring _B__91. This is the major excretory form of vitamin C: A. dehydroascorbic acid C. diketogulonic acid B. oxalic acid D. gulonolactone _B__92. In thiamine deficiency, severe muscle weakness occurs because: A. conversion of pyruvate to lactate does not take place B. conversion of pyruvate to acetyl CoA does not occur C. conversion of pyruvate to oxaloacetate does not take place D. conversion of pyruvate to ATP is blocked _D__93. Microcytic, hypochromic anemia is a deficiency manifestation of: A. Vitamin B6 C. Pantothenic acid B. Vitamin C D. A and B _A__94. This vitamin functions as coenzyme in the major anaphlerotic reaction of the body: A. Biotin C. Folic acid B. Pyridoxine D. Pantothenic acid _B__95. This is a test for folic acid deficiency: A. Tryptophan load test C. Glutamine load test B. Histidine load test D. Tyrosine load test _D__96. This function makes vitamin A anticarcinogenic: A. maintenance of the integrity of the RBC membrane B. maintenance of the integrity of the germinal epithelium C. maintenance of the integrity of mucopolysaccharides D. maintenance of the integrity of the epithelial tissues _B__97. Activation of vitamin D involves: A. a two-step reduction process C. a two-step hydrogenation process B. a two-step hydroxylation process D. a two-step oxidation process _B__98. This pathway can convert glucose to ascorbic acid: A. phosphogluconate pathway C. Embden-Meyerhof pathway B. glucuronic acid pathway D. Pentose phosphate pathway IMMUNOCHEMISTRY I. Immunity - Definition and significance - Classification as to active or passive, natural or artificial, innate or acquired II. Innate immunity - Cellular mediators – biochemical aspect of chemotaxis and phagocytosis - Soluble mediators: interleukins, interferons, complements III. Acquired immunity - cell-mediated immunity - humoral-mediated immunity IV. Hypersensitivity reactions QUESTIONS ON IMMUNOCHEMISTRY _C__99. Regarding the functions of the different classes of antibodies, which of the following statements is the most accurate? A. IgA acts as antigen receptor on the surface of B-cells B. IgG strongly activates the alternative pathway of the complement C. IgG coats the bacteria, making them easily engulfed by the phagocyte D. IgM defends against parasitic worm E. IgE blocks the binding of viruses to the gut mucosa _C__100. The following statements about immunity are true, EXCEPT: A. T-cells are components of an adaptive immunity B. The response after giving live measles virus vaccine is an example of active immunity C. Classical pathway of complement activation is under adaptive Immunity D. Production of antibodies after being infected with influenza virus Is a good example of natural immunity E. Gastric juices and tears belong to innate immunity. REFERENCE: Biochemistry (By Lehninger, Nelson Etal, Stryer) Principles of Biochemistry (By Zybay, Parson, Van) BOARD REVIEW QUESTIONS IN BIOCHEMISTRY 1. What is the ion product of water? A. It is the total number of negatively and positively charged ions in 1 liter of aqueous solution. B. It is the product of the concentrations of hydrogen and hydroxyl ions in an aqueous solution. C. It is the number of ionized molecules of water in 1 mole of pure water. D. It is the sum of all hydrogen and hydroxyl ions in an aqueous solution. Ans. B Ref: Harper’s Biochemistry 24th ed. pp.18-19 MPL: 0.75 2. A very anxious student hyperventilates an hour before the biochemistry board exam. What is the effect of hyperventilation on his Pco2 and blood pH? A. Pco2 decreases and pH increases. B. Pco2 decreases and pH decreases. C. Pco2 increases and pH decreases. D. Pco2 increases and pH increases. Ans. A Ref: Harper’s Biochemistry 24th ed. Pp. 18-19 MPL: 0.25 3. A protein rich in which of the following amino acids will provide the greatest buffering capacity at physiologic pH? A. Valine B. Aspartic acid C. Lysine D. Histidine Ans. D Ref: Harper’s Biochemistry 24th ed. p.26 MPL: 0.75 4. Which of the following laboratory results would best indicate metabolic alkalosis? A. Increased Pco2, increased pH, increased HCO3. B. Normal Pco2, increased pH, decreased HCO3. C. Increased Pco2, increased pH, normal HCO3. D. Decreased Pco2, increased pH, normal HCO3. Ans. A Ref: Harper’s Biochemistry 24th ed. p.304 MPL: 0.75 5. What is the property of water that will contribute the most to its ability to dissolve compounds? A. Very few interactive forces in its structure. B. Hydrogen bond formation between water and long-chain fatty acids. C. Covalent bond formation between salt and water. D. Hydrogen bond formation between water and biochemical molecules. Ans. D Ref: Harper’s Biochemistry 24th ed. p.15-17 MPL: 0.75 6. A child’s developmental progress is noted to stop at 2 years old. The following year, skeletal deformities appear. The child regresses to a vegetative state at 10 years old. Urine examination tests positive for glucosaminoglycans that include most likely which of the following? A. Collagen B. Glycogen C. GABA D. Heparan sulfate Ans. D Ref. Harper’s Biochemistry 24th ed. p. 673 MPL: 0.25 7. A 3-year old child is diagnosed to have Hurler’s syndrome. The diagnosis of Hurler’s syndrome is MOST efficiently made by analyzing the patient’s DNA for: A. A region of DNA that does not encode RNA. B. Alternative forms of the L-Iduronidase gene. C. The entire set of genes in one leukocyte. D. A nucleotide substitution in the L-Iduronidase gene. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 678 MPL: 0.25 8. Which of the following statements regarding a double-helical molecule of DNA is TRUE? A. All hydroxyl groups of pentoses are involved in linkages. B. Bases are perpendicular to the axis. C. Each strand is identical. D. Each strand replicates itself. Ans. B Ref: Harper’s Biochemistry 24th ed. p.386 MPL: 0.75 9. A human DNA sample is subjected to increasing temperature until its major fraction exhibit optical density changes. A minor fraction of the sample DNA is atypical because it required a higher temperature to denature. This atypical minor fraction of sample DNA must have a higher content of: A. Adenine + Cytosine B. Cytosine + Guanine C. Adenine + Thymine D. Adenine + Guanine Ans. B Ref: Harper’s Biochemistry 24th ed. p. 387-388 MPL: 0.75 10. A newborn baby has a sibling with sickle cell anemia and is at risk for this disease. The appropriate diagnostic test for sickle cell anemia in this baby would include which of the following? A. DNA amplification B. Hemoglobin antibodies C. Red cell counting D. DNA fingerprinting Ans. A Ref: Harper’s Biochemistry 24th ed. p. 468 MPL: 0.25 11. Which of the following would BEST describe polymorphism? A. One phenotype, multiple genotypes B. Non-random allele association C. One locus, multiple abnormal alleles D. One locus, multiple normal alleles Ans. D Ref: Harper’s Biochemistry 24th ed. p. 476 12. What is that process that occurs at the 5-position of Cytidine and is often correlated with gene inactivation? A. Gene conversion B. Sister chromatid exchange C. Gene rearrangement D. DNA methylation Ans. D Ref: Harper’s Biochemistry 24th ed. p.466 MPL: 0.75 13. Restriction Fragment Length Polymorphism (RFLP) analysis can only be used to follow the inheritance of a genetic disease if: A. The disease-causing mutation is at or closely linked to an altered restriction site. B. Proteins of mutated and normal genes migrate differently upon gel electrophoresis. C. Mutations are outside restriction sites so that cleaving still occurs. D. mRNA probes are used in combination with antibodies. Ans. A Ref: Harper’s Biochemistry 24th ed. p. 478 14. DNA polymerases synthesize DNA only in the 5’ to 3’ direction. However, at the replication fork, both parentral strands of DNA are being replicated with the synthesis of new DNA. How is it possible that while one strand is being synthesized in the 5’ to 3’ direction, the other strand appears to be synthesized in the 3’ to 5’ direction? This is best explained by: A. 3’ to 5’ DNA repair enzymes B. 3’ to 5’ DNA polymerase C. Okazaki fragments D. Lack of RNA primer on one of the strands. Ans. C Ref: Harper’s Biochemistry 24th ed. p407 MPL: 0.75 15. The chromosomes of mammalian cells are 20 times as large as those of Escherichia coli. How can replication of mammalian chromosomes be carried out in just a few minutes? A. The higher temperature of mammalian cells allows for an exponentially higher replication rate. B. Hundreds of replication forks work simultaneously on each piece of chromosomal DNA. C. Many RNA polymerases carry out replication simultaneously on chromosomal DNA. D. The presence of histones speeds up the rate of chromosomal DNA replication. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 407 16. Sickle cell anemia is the manifestation of homozygous genes for an abnormal hemoglobin molecule. The mutation in the beta-chain is known to produce a single amino acid change. The most likely mechanism for this mutation is: A. Two base insertion B. Three base deletion C. Nondysjunction D. Point mutation Ans. D Ref: Harper’s Biochemistry 24th ed. p. 734 17. A culture of bacteria not resistant to Tetracycline develops an infection from a virus that is derived from the lysis of tetracycline-resistant bacteria. Most of the bacterial progeny of the original culture is found to have become resistant to tetracycline. What phenomenon has occurred? A. Conjugation B. Recombination C. Transformation D. Transduction Ans. D Ref: Harper’s Biochemistry 24th ed. p. 471 MPL: 0.75 18. Following ultraviolet damage to DNA in the skin, which of the following is MOST likely to occur? A. A specific nuclease detects damaged areas. B. Purine dimmers are formed. C. Both strands are cleaved. D. Endonuclease removes the damaged strand. Ans. A Ref: Harper’s Biochemistry 24th ed. p. 814 MPL: 0.75 19. Which of the following statements about the genetic code is the MOST accurate? A. Information is stored as sets of dinucleotide repeats called codons. B. The code is degenerate. C. There are 64 codons, all of which code for amino acids. D. Information is stored as sets of trinucleotide repeats called codons. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 433-434 MPL: 0.75 20. Which of the following is provided by the Northern Blot Analysis? A. Detection of specific base pairs. B. Detection of DNA molecules. C. Detection of RNA molecules. D. Detection of proteins. Ans. C Ref: Harper’s Biochemistry 24th ed. p. 472-473 MPL: 1.0 21. In contrast to DNA polymerase, RNA polymerase: A. Fills in the gap between the Okazaki fragments. B. Works only in a 5’ to 3’ direction. C. Edits as it synthesizes. D. Synthesizes RNA primer to initiate DNA synthesis. Ans. D Ref: Harper’s Biochemistry 24th ed. p. 418 MPL: 0.75 22. The removal of introns and subsequent self-splicing of adjacent exons occurs in some portions of primary ribosomal RNA transcripts. The splicing of introns in mRNA precursors is: A. RNA-catalyzed in the absence of protein. B. Carried out by spliceosomes. C. Controlled by RNA polymerase. D. Regulated by RNA helicase. Ans. B Ref: Harper’s Biochemistry 24th ed. p.426 MPL: 0.75 23. What is the function of a promoter site on DNA? A. Transcribes repressor B. Initiates transcription C. Codes for RNA polymerase D. Regulates termination Ans. B Ref: Harper’s Biochemistry 24th ed. p. 420 MPL: 1.0 24. The “sigma factor” found in many bacteria is best described as a: A. Subunit of RNA polymerase responsible for the specificity of the initiation of transcription. B. Subunit of DNA polymerase that allows for the synthesis in both 5’ to 3’ and 3’ to 5’ directions. C. Subunit of the 50S ribosome that catalyzes peptide bond synthesis. D. Subunit of the 30S ribosome to which mRNA binds. Ans. A Ref: Harper’s Biochemistry 24th ed. p. 418 MPL: 0.75 25. A 23-year old man was rushed to the emergency room with nausea, vomiting, and abdominal pain. Remnants of the death-cap wild mushroom Amanita phalloides were noted upon laboratory examination of his vomitus. A liver biopsy indicates massive hepatic necrosis. Care is supportive. A major toxin of the death cap mushroom inhibits which of the following? A. DNA primase B. RNA nuclease C. DNA ligase D. RNA polymerase Ans. D Ref: Harper’s Biochemistry 24th ed. p. 420 MPL: 0.75 26. The consensus sequence 5’-TATAAAA-3’ found ineukaryotic genes is almost similar to a consensus sequence observed in prokaryotes. The consensus sequence is important as the: A. Only site of binding of RNA polymerase II. B. Promoter site for all RNA polymerases. C. Termination site for RNA polymerase II. D. First site of binding of a transcription factor for RNA polymerase II. Ans. D Ref: Harper’s Biochemistry 24th ed. pp. 421-422 MPL: 0.75 27. The so-called “caps” of RNA molecules: A. Allow tRNA to be processed. B. Occur at the 3’-end of tRNA. C. Are composed of poly A. D. Are unique to eukaryotic mRNA. Ans. D Ref: Harper’s Biochemistry 24th ed. p. 428 MPL: 1.0 28. In bacterial RNA synthesis, what is the function of the “rho” factor? A. It binds catabolite repressor to the promoter region. B. It increases the rate of RNA synthesis. C. It eliminates the binding of RNA polymerase to the promoter. D. It participates in the proper termination of transcription. Ans. D Ref: Harper’s Biochemistry 24th ed. p. 419 MPL: 1.0 29. Which of the following statements correctly describes the nucleolus of a mammalian cell? A. It differs from that found in bacterial cells in that histones are present. B. It may contain hundreds of copies of genes for different types of ribosomal RNAs. C. It synthesizes 5S rRNA. D. It synthesizes all ribosomal RNA primary transcripts. Ans. B Ref; Harper’s Biochemistry 24th ed. p. 428 MPL: 0.75 30. Which of the following statements correctly describes the synthesis of mammalian mRNA? A. Each mRNA often encodes several different proteins. B. Several different genes may produce identical mRNA molecules. C. Mammalian mRNA undergoes minimal modification during its maturation. D. The RNA sequence transcribed from a gene is identical to the mRNA that exits from nucleus to cytoplasm. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 427 MPL: 0.75 31. Certain amino acids are not part of the primary structure of proteins but are modified after translation. In scurvy, which amino acid that is normally part of collagen is not synthesized? A. Hydroxytryptophan B. Hydroxytyrosine C. Hydroxyhistidine D. Hydroxyproline Ans. D Ref: Harper’s Biochemistry 24th ed. pp. 668-669 MPL: 1,0 32. Immunoglobulin G (IgG) molecules can be characterized by which of the following statements? A. They are maintained at a constant level in the serum. B. They contain nucleic acids. C. They contain mostly carbohydrates. D. They can be separated into subunits with a reducing agent and urea. Ans. D Ref: Harper’s Biochemistry 24th ed. p.716 MPL: 1.0 33. Which of the following proteolytic enzymes is activated by acid hydrolysis of the proenzyme form? A. Trypsin B. Elastase C. Pepsin D. Carboxypeptidase Ans. C Ref: Harper’s Biochemistry 24th ed. p.636 MPL: 1.0 34. Which of the following amino acids is ionizable in proteins? A. Leucine B. Histidine C. Valine D. Alanine Ans. B Ref: Harper’s Biochemistry 24th ed. p. 294 MPL: 0.75 35. The oxygen carrier of muscle is the globular protein myoglobin. Which of the following amino acids is highly likely to be localized within the interior of the molecule? A. Arginine B. Aspartic acid C. Glutamic acid D. Valine Ans. D Ref: Harper’s Biochemistry 24th ed. p.53 MPL: 0.75 36. Which of the following statements concerning immunoglobulins is most accurate? A. IgE is the principal antibody in the serum. B. The heavy chains are similar in each class of immunoglobulin. C. The constant regions of the heavy chains are the same in each class of immunoglobulin. D. IgE is the major immunoglobulin found in external secretions. Ans. C Ref: Harper’s Biochemistry 24th ed. p.718 MPL: 1.0 37. Under normal conditions in the blood, which of the following amino acid residues of albumin is neutral? A. Arginine B. Aspartate C. Glutamine D. Histidine Ans. C Ref: Harper’s Biochemistry 24th ed. p. 294 MPL: 0.75 38. A child develops chronic diarrhea and liver inflammation in early infancy when the mother begins using formula that includes corn syrup. Evaluation of the child demonstrates sensitivity to fructose in the diet. Which of the following glycosides contains fructose and therefore should be avoided when feeding or treating this infant? A. Sucrose B. Oaubain C. Lactose D. Maltose Ans. A Ref: Harper’s Biochemistry 24th ed. p.135 MPL: 0.75 39. Which of the following carbohydrates would be most abundant in a diet of strict vegetarians? A. Amylose B. Lactose C. Cellulose D. Glycogen Ans. C Ref: Harper’s Biochemistry 24th ed. p. 141 MPL: 1.0 40. The major metabolic product under normal circumstances by erythrocytes and by muscle cells during intense exercise is recycled through the liver in the Cori cycle. The metabolite is: A. Oxaloacetate B. Glycerol C. Alanine D. Lactate Ans. D Ref: Harper’s Biochemistry 24th ed. p. 200-201 MPL: 0.75 41. Chronic alcoholics require more ethanol than do nondrinkers to become intoxicated because of a higher level of a specific enzyme levels, the availability of what other substance is rate-limiting in the clearance of alcohol? A. NADH B. NAD+ C. FADH D. FAD+ Ans. B Ref: Harper’s Biochemistry 24th ed. pp. 601-603 42. Following a fad diet of skimmed milk and yogurt, an adult female patient experiences abdominal distention, nausea, cramping, and pain followed by watery diarrhea. This set of symptoms is observed each time the said meal is consumed. A most likely diagnosis is: A. Steatorrhea B. Lactase deficiency C. Sialidase deficiency D. Lipoprotein deficiency Ans. B Ref: Harper’s Biochemistry 24th ed. p. 645 MPL: 0.1 43. A percentage of Filipino population may flush and feel discomfort after drinking small amounts of ethanol in alcoholic beverages. This reaction is due to genetic variation in an enzyme that metabolizes the liver metabolite of alcohol, which is: A. Methanol B. Acetone C. Acetaldehyde D. Glycerol Ans. C Ref: Harper’s Biochemistry 24th ed. p. 264 44. Which of the following enzymes catalyzes the high-energy phosphorylation of substrates during glycolysis? A. Pyruvate kinase B. Phosphoglycerate kinase C. Triosephosphate isomerase D. Glyceraldehyde-3-phosphate dehydrogenase Ans. D Ref: Harper’s Biochemistry 24th ed. p.176 MPL: 1.0 45. Which of the following enzymes is common to both glycolysis and gluconeogenesis? A. Pyruvate carboxylase B. Hexokinase C. Phosphoglycerate kinase D. Fructose 1,6-bisphosphatase Ans. C Ref: Harper’s Biochemistry 24th ed. p.194 MPL: 0.75 46. During the first week of a diet of 1500 calories per day, the oxidation of glucose via glycolysis in the liver of a normal 59-kg woman is inhibited by the lowering of which of the following? A. Citrate B. ATP C. Ketone bodies D. Fructose-2,6-bisphosphatase Ans. D Ref: Harper’s Biochemistry 24th ed. p.176 47. Familial fructokinase deficiency causes no symptoms because: A. Hexokinase can phosphorylate fructose. B. Most tissues utilize fructose. C. Liver fructose-1-phosphate aldolase is still active. D. Excess fructose spills into the bowel and is eliminated in the feces. Ans. A Ref: Harper’s Biochemistry 24th ed. p. 214 MPL: 0.75 48. A newborn begins vomiting after feeding, becomes severely jaundiced, and has liver disease. Treatment for possible sepsis is initiated, and the urine is found to have reducing substances. A blood screen for galactosemia is positive, and lactose-containing substances are removed from the diet. Lactose is toxic in this case because: A. Excess glucose accumulated in the blood. B. Galactose is converted to the toxic substance galactitol. C. Galactose itself is toxic in even small amounts. D. Glucose metabolism is shut down by excess galactose. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 205 49. Which of the following enzymes catalyzes phosphorylation with the use of inorganic phosphate? A. Hexokinase B. Phosphofructokinase C. Phosphoglycerate kinase D. Glyceraldehyde-3-phosphate dehydrogenase Ans. D Ref: Harper’s Biochemistry 24th ed. p. 179 MPL: 0.75 50. After a well-rounded breakfast, which of the following would be expected to occur? A. Increased activity of pyruvate carboxylase B. Decreased activity of acetyl CoA carboxylase C. Decreased rate of glycogenesis D. Decreased rate of protein synthesis Ans. C Ref. Harper’s Biochemistry 24th ed. p. 179 MPL: 0.75 51. The ability of hemoglobin to serve as an effective transporter of oxygen and carbon dioxide between lungs and tissue is explained by which of the ff. properties? A. The isolated heme group with ferrous iron binds oxygen much more avidly than carbon dioxide B. The α – and β – globin chains of hemoglobin have very fifferent primary structures than myoglobin C. Hemoglobin utilizes oxidized ferric iron to bind oxygen, in contrats to the ferrous ion myoglobin. D. In contrast to myoglobin, hemoglobin exhibits greater changes in secondary and tertiary structure after oxygen binding Ans. D Ref. Harper’s Biochemistry 24th ed. p. 436 MPL 0.75 52. Contraction of skeletal muscle is initiated by the binding of calcium to: A. Tropomyosin B. Troponin C. Myosin D. Actomyosin Ans B Ref. Harper’s Biochemistry 24th ed. p. 687-688 MPL: 0.75 53. Which of the following statements correctly describes transport of oxygen by hemoglobin? A. Oxygen binds to hemoglobin more avidly than does carbon monoxide. B. The binding of oxygen to hemoglobin causes a valence change in the iron of the heme moiety. C. Each of the four heme moieties binds oxygen independently D. The plot of percentage of oxygen bound versus oxygen pressure is sigmoid in shape Ans. D Ref. Harper’s Biochemistry 24th ed. p. 436 MPL: 0.75 54. Which of the following mutations would produce a severe form of thalassemia? A. Deletion of one α-globin locus B. Deletion of one β-globin locus C. Oxidation of heme groups to produce methemoglobin D. Altered RNA processing at both Ans. D Ref. Harper’s Biochemistry 24th ed. p. 734 MPL 0.75 55. The substitution of valine for glutamate at position 6 on the two β chains in sickle cell hemoglobin causes which of the following? A. Increased electrophoretic mobility at pH 7.0 B. Increased solubility of deoxyhemoglobin C. Decreased polymerization of deoxyhemoglobin D. Unchanged primary structure Ans. A Ref. Harper’s Biochemistry 24th ed. p. 476 MPL 0.75 56. An increased affinity of hemoglobin for oxygen may result from which of the following? A. Initial binding of oxygen to one of the four sites available in each deoxyhemoglobin molecule B. High pH C. High carbon dioxide levels D. High 2,3-bisphosphoglycerate levels within erthrocytes Ans. A Ref. Harper’s Biochemistry 24th ed. p. 436 MPL 0.75 57. The functions of many enzymes, membrane transporters, and other proteins can be quickly activated or deactivated by phosphorylation of specific amino acid residues catalyzed by enzymes called: A. Cyclases B. Kinases C. Phosphatases D. Proteases Ans B Ref. Harper’s Biochemistry 24th ed. p. 64-65 MPL 0.75 58. The chemotherapeutic drug fluoracil undergoes a series of chemical changes in vivo that results in a complex such that it is bound to both thymidylate synthase and methylene-tetrahydrofolate. The inhibition of deoxythymidylate formation and subsequent blockage of cell division is due to: A. Allosteric inhibition B. Competitive inhibition C. Irreversible inhibition D. Non-covalent inhibition Ans C Ref. MPL Harper’s Biochemistry 24th ed. p. 86-88 0.75 59. The Vmax of the enzyme is the: A. Reciprocal of the absolute value of the intercept of the curve with the x-axis B. Reciprocal of the absolute value of the intercept of the curve with the y-axis C. Absolute value of the intercept of the curve with the x-axis D. Slope of the curve Ans B Ref. Harper’s Biochemistry 24th ed. p. 75-90 MPL 0.75 60. In the study of enzymes, the sigmoidal plot of substrate concentration versus reaction velocity may indicate: A. Michaelis-Menten Kinetics B. Myoglobin binding oxygen C. Cooperative binding D. Competitive inhibition Ans C Ref. Harper’s Biochemistry 24th ed. p. 75, 90 MPL 1.0 61. A non competitive inhibitor of an enzyme: A. Increases Km with no or little change in Vmax B. Decreases Km and decreases Vmax C. Decreases Vmax D. Increases Vmax Ans C Ref. Harper’s Biochemistry 24th ed. p. 86-88 MPL 0.75 62. Which of the following statements correctly describes allosteric enzymes? A. Effectors may enhance or inhibit substrate binding B. They are not usually controlled by feedback inhibition C. The regulatory site may be catalytic site D. Michaelis-Menten kinetics describe their activity Ans A Ref. Harper’s Biochemistry 24th ed. p. 104-105 MPL 0.75 63. Which of the following enzymes is regulated primarily through allosteric interaction? A. Chymotrypsin B. Pyruvate dehydrogenase C. Glycogen phosphorylase D. Aspartate transcarbamoylase Ans D Ref. Harper’s Biochemistry 24th ed. p. 104-105 MPL 0.75 64. A comatose laboratory technician is rushed into the emergency room. She dies while you are examining her. Her most dramatic symptom is that her body is literally hot to your touch, indicating an extremely high fever. You learn that her lab has been working on metabolic inhibitors and that there is a high likelihood that she accidentally ingested one. Which one of the following is the MOST likely culprit? A. Barbiturates B. Piericidin A C. Dimercaprol D. Dinitrophenol Ans D Ref. Harper’s Biochemistry 24th ed. p. 128 MPL 0.25 65. Which of the following statements about flavoproteins is TRUE? A. They are not oxidized by coenzymeQ B. They receive electrons from cytochrome P450 in liver mitochondria C. They do not participate in oxidation of NADH dehydrogenises D. They can be associated with sulfur and nonheme iron Ans D Ref. Harper’s Biochemistry 24th ed. p. 117-118 MPL 0.75 66. As electrons are received and passed down the transport chain, the various carriers are first reduced with acceptance of the electron and then oxidized with loss of the electron. A patient poisoned by which of the following compounds has the MOST highly reduced state of the respiratory chain carriers? A. Antimycin A B. Rotenone C. Carbon Monoxide D. Puromycin Ans C Ref. Harper’s Biochemistry 24th ed. p. 128 MPL 0.25 67. Which of the following compounds is a member of the electron transport chain? A. Octanoyl carnitine B. Cytochrome c C. NADH D. Palmitoyl carnitine Ans C Ref. Harper’s Biochemistry 24th ed. p. 128 MPL 0.75 68. All known effects of cyclic AMP in eukaryotic cells result from: A. Activation of the catalytic unit of adenylate cyclase B. Activation of synthetases C. Activation of protein kinase D. Stimulation of calcium release from the endoplasmic reticulum Ans C Ref. Harper’s Biochemistry 24th ed. p. 165 MPL 0.75 69. The connection between oxidative phosphorylation and electron transport is BEST described by: A. Existence of higher pH in the cisternae of the endoplasmic reticulum than in the cytosol. B. Synthesis of ATP as protons into the mitochondrial matrix along a proton gradient that exist across the inner mitochondrial membrane C. Dissociation of electron transport and oxidative phosphorylation D. Absence of ATPase in the inner mitochondrial membrane Ans B Ref. Harper’s Biochemistry 24th ed. p. 127 MPL 0.75 70. If all potential sources of ATP production are taken into account, the net number of ATP molecules formed per molecule of glucose in aerobic glycolysis is: A. 2 B. 6 C. 18 D. 36 Ans B Ref. Harper’s Biochemistry 24th ed. p. 176-184 MPL 0.75 71. Which of the following reactions generates ATP/ A. Glucose 6-phosphate to Fructose 6-phosphate B. Glucose to Glucose 6-Phosphate C. Fructose 6-phosphate to Fructose 1,6-bisphosphate D. Phosphoenolpyruvate Ans D Ref. Harper’s Biochemistry 24th ed. p. 176-184 MPL 0.75 72. which of the following products of triacylglycerol breakdown and subsequent β-oxidation may undergo gluconeogenesis? A. Propionyl CoA B. Acetyl CoA C. All ketone bodies D. Some amino acids Ans A Ref. Harper’s Biochemistry 24th ed. p. 284 MPL 0.75 73. Which of the following regulates lipolysis in adipocytes? A. Activation of fatty acid synthesis mediated by cAMP B. Activation of triglyceride lipase as a result of hormone-stimulated increases in cAMP production by insulin C. Glyerol phosphorylation to prevent futile esterification of fatty acids D. Activation of cAMP production by insulin Ans D Ref. Harper’s Biochemistry 24th ed. p. 267 74. Inhibition of ATP synthesis during oxidative phosphorylation by oligomycin is thought to be due to: A. Blocking of the proton gradient between NADH-Q reductase & QH2 B. Blocking of the proton gradient between cytochrome C1 and cytochrome C C. Dissociation of cytochrome c from mitochondrial membranes D. Inhibition of mitochondrial ATPase Ans D Ref. Harper’s Biochemistry 24th ed. p. 701 MPL 0.75 75. The reactions of the urea cycle occur: A. In the cytosol B. In the mitochondrial matrix C. In the mitochondrial matrix & the cytosol D. Only in lysosomes Ans C Ref. Harper’s Biochemistry 24th ed. p. 301-380 MPL 0.75 76. A newborn becomes progressively lethargic after feeding and increases his respiratory rate. He becomes virtually comatose, responding only to painful stimuli, and exhibits mild respiratory alkalosis. Suspicion of urea cycle disorder is aroused and evaluation of serum amino acids levels is initiated. In the presence of hyperammonemia, production of which of the following amino acids is always increased? A. Glycine B. Arginine C. Proline D. Glutamine Ans D Ref. Harper’s Biochemistry 24th ed. p. 267 MPL 0.75 77. The thyroid hormone thyroxine (T 4) is derived from: A. Threonine B. Tyrosine C. Thiamine D. Tryptophan Ans B Ref. Harper’s Biochemistry 24th ed. p. 534-536 MPL 0.75 78. Which of the metabolites below is a precursor of tyrosine? A. L-dihydroxyphenylalanine (DOPA) B. Dopamine C. Norepinephrine D. Phenylalanine Ans D Ref. Harper’s Biochemistry 24th ed. p. 296-297 MPL 0.75 79. Which clinical laboratory observation is suggestive of Hartnup’s disease? A. High fecal levels of tryptophan and indole derivatives B. Elevated plasma tyrosine and methionine levels C. Elevation of glutamine in blood and urine D. Extremely high levels of citrulline in urine Ans A Ref. Harper’s Biochemistry 24th ed. p. 322-325 MPL 0.75 80. The important receive group of glutathione in its role as antioxidant is: A. Serine B. Sulfhydryl C. Tyrosine D. Acetyl CoA Ans B Ref. Harper’s Biochemistry 24th ed. p. 753 MPL 0.75 81. A newborn develops jaundice that requires laboratory evaluation. Which of the following porphyrin derivatives is conjugated, reacts directly, and is a major component of bile? A. Stercobilin B. Biliverdin C. Bilirubin D. Bilirubin diglucuronide Ans D Ref. Harper’s Biochemistry 24th ed. p. 356 MPL 0.75 82. Which of the following poryphrins give stools their characteristic brown color? A. Biliverdin B. Urobilinogen C. Heme D. Stercobilin Ans D Ref. Harper’s Biochemistry 24th ed. p. 354 83. Chylomicrons, IDL, LDL, and VLDL are all serum lipoproteins. What is the correct ordering of these particles from the lowest to the highest density? A. LDL, IDL, VLDL, Chylomicrons B. Chylomicrons, VLDL, IDL, LDL C. VLDL, IDL, LDL, Chylomicrons D. Chylomicrons, IDL, VLDL, LDL Ans B Ref. Harper’s Biochemistry 24th ed. p. 708 MPL 0.75 84. Ceramide is a precursor to which of the following compounds? A. Phosphatidyl serine B. Sphingomyelin C. Phosphatidyl glycerol D. Phosphatidyl choline Ans B Ref. Harper’s Biochemistry 24th ed. p. 250-252 MPL 0.75 85. Which of the following steps in cholesterol biosynthesis is thought to be rate-limiting and the locus of metabolic regulation? A. Geranyl pyrophosphate to Farnesyl pyrophosphate B. Squalene to Lanosterol C. Lanosterol to Cholesterol D. 3-hydroxy-3-metylglutaryl CoA to Mevalonic acid Ans B Ref. Harper’s Biochemistry 24th ed. p. 274 86. Humans MOST easily tolerate a lack of which of the following nutrients? A. Protein B. Iodine C. Carbohydrate D. Lipid Ans C Ref. Harper’s Biochemistry 24th ed. p. 285-286 MPL 0.75 87. A deficiency in Vitamin B12 causes: A. Cheilosis B. Beriberi C. Pernicious anemia D. Scurvy Ans D Ref. Harper’s Biochemistry 24th ed. p. 612-613 88. Which of the following vitaminswould MOST likely become deficient in a person who develops a completely carnivorous lifestyle? A. Thiamine B. Niacin C. Cobalamin D. Vitamin C Ans D Ref. Harper’s Biochemistry 24th ed. p. 612-613 MPL 0.75 89. Fully activated pyruvate carboxylase depends upon the presence of: A. Malate and Niacin B. Acetyl CoA and Biotin C. Acetyl CoA and Thiamine pyrophosphate D. Oxaloacetate Ans B Ref. Harper’s Biochemistry 24th ed. p. 194 90. Biotin is involved in which of the following types of reactions? A. Hydroxlations B. Carboxylations C. Decarboxylations D. Dehydrations Ans B Ref. Harper’s Biochemistry 24th ed. p. 606-607 MPL 0.75 91. Which of the following conditions would primarily produce a functional deficiency of Vitamin K? A. Coumadin Therapy B. Broad Spectrum antibiotic C. Premature birth D. Lack of red meat in the diet Ans Ref. MPL A Harper’s Biochemistry 24th ed. p. 727 0.75 92. A 3 month old boy presents with poor feeding & growth, hypotonia, lactic acidemia, and mild acidosis. The pyruvate to lactate ratio is high, and there is decreased conversion of pyruvate to Acetyl CoA. Which of the following may be considered for therapy? A. Thiamine B. FFA C. Biotin D. Vitamin C Ans A Ref. Harper’s Biochemistry 24th ed. p. 183 MPL 0.25 93. A 2-year old child presents with cough and bronchitis, growth failure, & chronic diarrhea with lightcolored foul smelling stools. A deficiency of which vitamin should be considered? A. Vit B6 B. Vit C C. Vit A D. Vit B1 Ans C Ref. Harper’s Biochemistry 24th ed. p. 614-617 MPL 0.25 94. an infant presents with prominent forehead, bowing of the limbs, broad & tender wrists, swelling at the costochondral junction of the ribs, and irritability. Which of the following treatments is the most appropriate for this patient? A. Removal of eggs from diet B. Milk & Sunlight exposure C. Diet of baby food containing liver & ground beef D. Diet of baby food containing leafy vegetables Ans C Ref. Harper’s Biochemistry 24th ed. p. 613 MPL 0.25 95. Allopurinol effectively treats gout but has NO effect on the severe neurological symptoms of LeschNyhan patients because it does not: A. Decrease de Novo purine synthesis B. Decrease de Novo Pyrimidine syntheis C. Inhibit xanthine oxidase D. Increase PRPP levels Ans A Ref. Harper’s Biochemistry 24th ed. p. 378 MPL 0.75 96. Which of the following would rule out hyperuricemia in a ptient? A. Lesch-Nyhan synthesis B. Gout C. Carbonage phosphate deficiency D. Xanthine oxidase hyperactivity Ans C Ref. Harper’s Biochemistry 24th ed. p. 381 MPL 0.75 97. Which of the following contributes nitrogen atom to both purine & pyrimidine rings? A. Aspartate B. Carbonage PO4 C. CO2 98. What is the end product of fatty acid synthase activity in human? A. Palmitic acid B. Palmetoleic acid C. Linoleic D. Arachidonic acid Ans A Ref. Harper’s Biochemistry 24th ed. p. 216-223 MPL 0.75 99. For every 2 moles of free glycerol released by lipolysis of triglycerides in adipose tissue? A. 1 mole of glucose can be synthesized via gluconeogenesis B. 2 moles of triacylglyceride is released C. 2 moles of FFA is released D. 3 moles of Acyl CoA is produced Ans A Ref. MPL Harper’s Biochemistry 24th ed. p. 267 0.75 100. A 45 year old man ha s a mild heart attack and is placed on diet and Metastatin therapy. Which of the following will result in this therapy? A. Low blood glucose level B. Low blood LDLs C. High blood cholesterol D. Low oxidation of Fa Ans B Ref. Harper’s Biochemistry 24th ed. p. 281 MPL 0.75 B. MEDICAL BOARD REVIEW QUESTIONS 1. The functional groups of amino acids include: A. carboxyl and alpha carbon C. amino and carboxyl groups B. amino group and side chain D. alpha carbon and hydrogen Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 18. 2. Which of the following amino acids contains a polar side chain? A. Alanine C. Proline B. Serine D. Methionine Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 16. 3. Which amino acid is considered as purely ketogenic? A. Leucine C. Isaoleucine B. Lysine D. Valine Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 232. 4. The chemical bond that connects amino acids to form a polypeptide chain is: A. glycosidic bond C. van der Waals B. peptide bond D. hydrogen bond Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 238. 5. The primary sequence of proteins is determined by: A. mRNA C. tRNA B. DNA D. hnRNA Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 235. 6. Maple syrup disease is a genetic abnormality that affects the catabolism of: A. aromatic amino acids C. glycogen B. branched -chain amino acids D. lipoproteins Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p.259. 7. The first reaction in the catabolism of amino acid is: A. deamination C. oxidation B. decarboxylation D. dehydrogenation Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 243. 8. The final product from the catabolism of amino acids is: A. uric acid C. ammonia B. urea D. nitrogen Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 243. 9. The enzyme that catalyzes the reaction to release nitrogen as ammonia in the liver is: A. glutamine synthetase C. glutamine amidotransferase B. L-glutamate dehydrogenase D. alanine transaminase Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 242. 10. The enzyme that catalyzes the rate-limiting reaction in the urea synthesis is: A. glutamine synthetase C. carbamoyl phosphate synthetase B. alpha-ketoglutarate dehydrogenase D. ornithine decarboxylase Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 243. 11. Enzymes are need in metabolic reactions because they: A. serve as activators C. modify the configuration of the substrates B. act to stabilize reaction rates D. increase the rate of reaction Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 50. 12. The catalytic activity of the enzyme is located at: A. binding site C. cofactor B. active site D. coenzyme Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 51. 13. What is the effect of temperature on enzyme activity? A. substrate binding C. denaturation of the enzyme B. ionization of coenzyme D. ionization of the enzyme Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 55. 14. The Km or Michaelis constant is a measure of the: A. rate of reaction C. Vmax B. equilibrium constant D. affinity of the substrate to the enzyme Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 65. 15. A structural analogue of the substrate that can bind to the active site is called: A. noncompetitive inhibitor C. irreversible inhibitor B. competitive inhibitor D. uncompetitive inhibitor Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 65. 16. Attachment site of amino acids to the tRNA molecule is called: A. anticodon C. variable loop B. D loop D. acceptor stem Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 361. 17. Termination of translation is signaled when the reading frame contains: A. AUG C. UAG B. AGA D. AGU Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 370. 18. The domain of RNA polymerase that identifies the initiation site for transcription is: A. rho factor C. tata box B. sigma factor D. hogness box Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 342. 19. The noncoding sequence in mRNA is called: A. exon C. cistron B. muton D. intron Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 341. 20. The adapter molecule during translation is: A . tRNA C. rRNA B. mRNA D. DNA Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 355. 21. The enzyme that catalyzes replication in Hepatitis B virus: A. DNA polymerase C. reverse transcriptase B. RNA polymerase D. restriction enzyme Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 333. 22. Which of the following contains clones that reflect mRNA sequences? A. cDNA library C. clone B. DNA library D. cosmids Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 413. 23. The vector used in recombinant DNA techniques that allows cloning of large DNA fragments is: A. Plasmid C. Bacteriophage B. Cosmid D. Intron Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 410. 24. The enzyme that catalyzes the rate-limiting step in the de novo synthesis of purine nucleotides is: A. hypoxanthine-guanine phosphoribosyl transferase B. xanthine oxidase C. phosphoribosyl phosphate synthetase D. phosphoribosyl phosphate amidotransferase Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 293. 25. The first purine nucleotide synthesized during the de novo pathway is: A. AMP C. IMP B. GMP D. ADP Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 293. 26. Which enzyme participates in both salvage and de novo synthesis of purine and pyrimidine nucleotides? A. Adenosine phosphoribosyl transferase B. xanthine oxidase C. phosphoribosyl phosphate synthetase D. phosphoribosyl phosphate amidotransferase Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 294. 27. The primary product of purine catabolism is: A. xanthine C. uric acid B. urea D. hypoxanthine Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p.299. 28. The salvage pathway of purine nucleotide is described as: A. utilizing amphibolic intermediates. B. is less active than the de novo synthesis C. is catalyzed by phosphoribosyl transferase D. requiring more energy than the de novo pathway Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 294. 29. Which molecule is NOT a monomer of ribonucleic acids? A. adenine C. cytidine B. thymine D. uridine Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 303. 30. The Watson - Crick model of DNA is described as: A. A right handed double helix with the bases directed inwards A. containing 12 base pairs B. having a pitch of 33A C. the A DNA Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 305. 31. The discontinuous polymerization of DNA results in the synthesis of: A. Okazaki fragments C. exons B. RNA D. introns Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 330. 32. The following is TRUE of hemoglobin: A. The ligand affinity to O2 is affected by allosteric factors: B. Its tetrameric structure ensures a sigmoidal dissociation curve in all instances. C. Its quarternary interface interactions modify its O2 transport function. D. Quarternary structural changes occur only in binding with oxygen molecules. Reference: Lehninger, A. et. al., Principles of Biochemistry, 3rd ed., p.s-9 33. The following statement pertains to HCO3- formation in the body: A. Carbonic anhydrase exist in substantial amounts in the RBC as well as in the plasma. B. To be catalytically active, carbonic anhydrase requires the alignment of multiple positive changes in the hemoglobin molecule. C. The presence of zinc in the enzyme enhances the release of a proton (H +) to generate a OH- ion. D. HCO3- formed binds preferentially to deoxyhemoglobin than to oxyhemoglobin. Reference: Lehninger, A. et. al., Principles of Biochemistry, 3rd ed., p.s-15 34. The following statements pertain to Bohr effect: A. Bohr effect explains why Hgb F does NOT bind BPG (bisphosphoglycerate). B. Bohr effect refers to the change in hemoglobin 's ligand affinity to O2 (p50) due to increase in body temperature. C. Bohr effect refers to the change in position of Fe++ and proximal histidine when the sixth coordination site is occupied by O2. D. Bohr effect describes how ↓pH provides the proton to form the salt bridges of deoxyhemoglobin. Reference: Lehninger, A. et. al., Principles of Biochemistry, 3rd ed., p.s-15 35. After exposing a jaundiced infant to phototherapy, the following is true of bilirubin excretion: A. Bilirubin is converted to bilirubin diglucoronide. B. Phototherapy provides the sulfates needed to conjugate bilirubin. C. Bilirubin will be excreted in the feces as mesobilirubin. D. Increased amounts of urobilin is found in the urine. Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 280. 36. The fibrinolytic system of the coagulation system is characterized by: A. stabilization of the fibrin molecules by covalent cross-linkage bonding. B. glycoproteins that regulate coagulation mechanism. C. components which are thiol-dependent transglutaminases. D. glycoproteins that contain serine dependent active protease sites. Reference: Murray, R.K., et. al., Harper's Illustrated Biochemistry, 26th ed., p. 604. 37. Which of the following conditions can lead to water excess? A. Diabetes mellitus C. Persistent vomiting B. Diabetes insipidus D. Congestive heart failure Reference: Berg, J. M., et. al., Biochemistry, 5th ed., p. 858. 38. An exergonic reaction is one that: A. has a positively charge standard change in free energy. B. needs an input of energy. C. is spontaneous in nature. D. is exemplified by anabolic reaction. Reference: Murray, R.K., et. al., Harper's Biochemistry, 25th edition, p.123. 39. The free energy change of a chemical reaction indicates which of the following? A. The spontaneity of a chemical reaction. B. The rate of a chemical reaction. C. The product of a chemical reaction. D. The reactants of the chemical reaction. Reference: Murray, R.K., et. al., Harper's Biochemistry, 25th edition, p.123. 40. The first law of thermodynamics states that the: A. energy of the universe remains constant at all times. B. energy cannot be transformed to another form. C. for a chemical reaction to proceed, there must be an increase in entropy. D. endergonic reaction must be coupled to exergonic reactions. Reference: Murray, R.K., et. al., Harper's Biochemistry, 25th edition, p.123. 41. According to Mitchell's chemiosmotic theory, oxidative phosphorylation is dependent on: A. the concentration differences with the reduced co-enzyme and the oxidized form. C. formation of high-energy intermediate during the flow of electrons. D. change in the conformation of proteins in the inner mitochondrial membrane. E. protons and pH gradients created between the intermembranous space and the mitochondrial matrix. Reference: Murray, R.K., et. al., Harper's Biochemistry, 25th edition, p.143. 42. Which of these fatty acids is a precursor of the prostaglandins? A. Palmitic acid C. Oleic acid B. Arachidonic acid D. Propionic acid Reference: Champe, P. C., et al., Biochemistry, 2nd ed., p. 185 43. Which of the following ketone bodies cannot produce energy upon oxidation? A. -hydroxybutyrate C. Acetone B. HMG CoA D. Acetoacetate Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 244. 44. The immediate substrate for ketogenesis is: A. Acetyl CoA C. Malonyl CoA B. Fatty acyl CoA D. Citrate Reference: Murray, R. K., et. Al., Harper’s Biochemistry, 25 th ed., p. 244. 45. The major source of NADPH for fatty acid synthesis is: A. Pentose phosphate pathway . B. Isocitrate dehydrogenase reaction C. Decarboxylation of malate to pyruvate in the cytoplasm D. -ketoglutarate dehydrogenase reaction Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 232. 46. Hypercholesterolemic drugs inhibit this enzyme which catalyze the rate-limiting step in cholesterol synthesis: A. HMG CoA reductase C. Cholesteryl esterase B. Squalene monooxygenase D. Mevalonate kinase Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 286. 47. In the heart, the major source of energy for oxidative metabolism is: A. Glucose C. Fatty acids B. Lactate D. Amino acids Reference: Murray, R. K., et. al. Illustrated Biochemistry, 26th ed., p. 235. 48. Which of the following is a characteristic of the cholesterol stones? A. They are usually formed during passage of the bile through the hepatic bile ducts. B. They occur when the mixed phospholipids-bile acid micelles are very high in phospholipids. C. They can be dissolved by excess bile acids because the bile acids help to solubilize in micelles the water insoluble cholesterol. D. They rarely occur because cholesterol is not a normal part of the bile. Reference: Devlin, F. M., Textbook of Biochemistry with Clinical Correlations, 5th ed., p.1114. 49. The key regulatory enzyme of fatty acid synthesis is: A. Fatty acid synthase C. Citrate synthase B. Acetyl CoA carboxylase D. Malonyl transacylase Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 230. 50. Which transport system shuttles activated fatty acid molecule from the cytoplasm to the inner mitochondrial membrane during β-oxidation of fatty acids? A. Citrate shuttle C. Malate-aspartate shuttle B. Carnitine shuttle D. Glycerol phosphate Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 239. 51. The rate-limiting step of fatty acid oxidation is: A. activation of fatty acid B. provision of fatty acid C. transport of fatty acyl CoA into the mitochondrion D. formation of malonyl CoA Reference: Murray, R. K. et. al., Harper’s Biochemistry, 25th ed., p. 239. 52. Complete oxidation of a saturated 21-carbon fatty acid yields how many molecules of ATP? A. 161 C. 165 B. 163 D. 167 Reference: Champe, P. C., et. al., Biochemistry, 2nd ed., p. 185. 53. Carbohydrate digestion stops temporarily in the stomach because: A. carbohydrates are already digested upon reaching the stomach. B. the low gastric pH inactivates amylase. C. there are no digestive enzymes in the stomach. D. the stomach lacks the activators for amylase. Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 662. 54. Which glycolytic reaction step reoxidizes NADH2 to NAD+ and reduces pyruvate to lactate? A. Glyceraldehyde 3-phosphate dehydrogenase reaction B. Pyruvate kinase reaction C. Lactate dehydrogenase reaction D. Phosphofructokinase reaction Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 194. 55. Which of the following compounds are involved in storing energy? A. Glycogen C. ATP B. Triacylglycerol D. A and B Reference: Murray, R. K., et. al, Illustrated Biochemistry, 26th ed., pp. 458-460. 56. Glucose absorption from the intestinal mucosal cell is characterized as: A. an energy-independent carrier mediated system. B. a co-transport system with sodium. C. transport of glucose along concentration gradient. D. passive diffusion of glucose across the intestinal epithelial cell. Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 667. 57. Glucose is a precursor of ribose and deoxyribose moieties of nucleotides and deoxynucleotides via which of the following pathways? A. Uronic acid pathway C. Pentose phosphate pathway B. Glucose-Alanine Cycle D. Polyol pathway Reference: Champe, P. C., et. al., Biochemistry, 2nd ed., p. 42. 58. Which of the following is TRUE of gluconeogenesis? A. It results to a net synthesis of ATP. B. Acetyl CoA can be converted to glucose. C. Muscles and brain can contribute to blood glucose. D. The pathway is stimulated by decreased AMP levels. Reference: Murray, R. K. et. al., Harper’s Biochemistry, 25th ed.,. pp. 208-215. 59. Which of the following enzymes do not catalyze a rate-controlling step in the citric acid cycle? A. Fumarase C. Citrate synthase B. Isocitrate dehydrogenase D. β-ketoglutarate dehydrogenase Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., pp184-186. 60. Which enzyme reverses the hexokinase reaction in the liver during fasting to liberate free glucose into the blood? A. Glucose 6-phosphatase C. Pyruvate carboxylase B. PEP carboxykinase D. Fructose 1,6-bisphosphatase Reference: Murray, R. K. et. al., Illustrated Biochemistry, 26th ed., pp. 119-120. 61. Insulin stimulates which of the following metabolic pathways? A. Glycogenolysis C. Gluconeogenesis B. Glycolysis D. Lipolysis Reference: Murray, R.K., et. al., Illustrated Biochemistry, 26th ed., p. 156. 62. Which is NOT an intermediate of the Krebs Cycle? A. Isocitrate C. Succinate B. Pyruvate D. Malate Reference: Murray, R.K., et. al., Illustrated Biochemistry, 26th ed., pp. 130-132. 63. The process by which ATP is formed as a result of the transfer of electrons from NADH or FADH2 to oxygen by a series of electron carriers is called: A. substrate level phosphorylation C. phosphorylation of an enzyme B. oxidative phosphorylation D. dephosphorylation of an enzyme Reference: Murray, R.K., et. al., Illustrated Biochemistry, 26th ed., p. 94. 64. Which of the following vitamins acts as a carrier of carbon dioxide in most carboxylation reactions? A. Thiamine C. Biotin B. Cobalamin D. Folic acid Reference: Murray, R. K., et. al., Illustrated Biochemistry, 26th ed., p. 494. 65. The fat soluble vitamin under current investigation for its cardioprotective properties is: A. Vit. A C. Vit. E B. Vit. D D. Vit. K Reference: Champe, P. C., et. al., Biochemistry, 2nd ed., p. 315. 66. The active form of vitamin D is: A. 7-dehydrocholesterol C. 1,25-dihydrocholecalciferol B. cholecalciferol D. 24,25-dihydroxycholecalciferol Reference: Champe, P. C., et. al, Biochemistry, 2nd ed., p. 335. 67. The effects of vitamin A may include all of the following EXCEPT: A. prevention of anemia. C. the visual cycle B. serving as an antioxidant D. induction of certain cancers Reference: Champe, P. C. et. al., Biochemistry, 2nd ed., pp. 330-332. 68. This mineral ion is a necessary co-factor in all reactions where ATP participates: A. Cu+2 C. Fe+2 +2 B. Mn D. Mg+2 Reference: Berg, J. M., et. al., Biochemistry, 5th ed., p. 254. 69. The second messenger of glucagon is: A. cyclic AMP C. cyclic GMP B. Tyrosine kinase D. Calcium Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 535. 70. Which of the following hormones activates the hormone response element? A. Thyroxine C. Glucagon B. Epinephrine D. Growth hormone Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 537. 71. A hormone which is virilizing and can stimulate somatic growth is: A. Estrogen C. Progesterone B. Androgen D. Prolactin Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25thed., p. 598. 72. The following is NOT a cholesterol derived hormone: A. Thyroxine C. Androgens B. Calcitriol D. Estrogens Reference: Murray, R. K, et. al., Harper’s Biochemistry, 25th ed., 535. 73. Intracellular calcium is mobilized ion the cytoplasm by this PIP2-derived second messenger: A. Protein kinase C C. Inositol diphosphate B. Inositol triphosphate D. Phosphatidylinositol Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 546. 74. A transducing protein found in cell membranes which when actrivated after hormone receptor interaction activates the adenylate cyclase system: A. Ubiquitin C. G-protein B. Calmodulin D. Protein kinase Reference: Murray, R. K., et. al. Illustrated Biochemistry, 26th ed., pp. 458-460. 75. The most significant source of stored energy in the human body is: A. Liver glycogen C. Adipose tissue fats B. Muscle proteins D. Brain glucose Reference: Campbell, M. K., Bichemistry, 3rd ed., p. 574. 76. Positive nitrogen balance is encountered in all of the following EXCEPT: A. Kwashiorkor C. Growth B. Convalescence D. Pregnancy Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 656. 77. The greatest fraction of the total energy requirement of an individual is provided by: A. Basal metabolism C. Diet-induced thermogenesis B. Specific dynamic action of food D. Physical activity Reference: Murray, R. K., et. al., Harper’s Biochemistry, 25th ed., p. 655. 78. Which of the following individuals would most likely be in nitrogen equilibrium? A. a normal, adult male C. a growing child B. a normal, pregnant female D. an adult male recovering from surgery Reference: Devlin, F. M., Textbook of Biochemistry with Clinical Correlations, 5th ed., p. 1133. 79. Which of the following statements about dietary fibers is/are correct? A. Water soluble fiber helps to lower serum cholesterol in most people. B. Mucilaginous fiber slows the rate of digestion and absorption of carbohydrates. C. Insoluble fiber increases stool bulk and decreases transit time. D. All of the above are correct. Reference: Devlin, F. M, Textbook of Biochemistry with Clinical Correlations, 5th ed., p.1134. 80. A complete replacement of animal protein in the diet by vegetable protein: A. would be expected to have no effect at all on the overall diet. B. would reduce the total amount of food consumed for the same number of calories. C. might reduce the total amount of iron and Vitamin B12 available. D. would be satisfactory regardless of the nature of the vegetable protein used. Reference: Devlin, F. M., Textbook of Biochemistry with Clinical Correlations, 5th ed., p. 1134. 81. Which of the following dietary regimens would be most effective in lowering cholesterol? A. Restrict dietary cholesterol B. Increase the ration of polyunsaturated to saturated fatty acids. C. Restrict cholesterol and increase fiber. D. Restrict cholesterol, increase PUFA/SFA and increase fiber. Reference: Devlin, F. M., Textbook of Biochemistry with Clinical Correlations, 5th ed., p. p.1134. 82. The main source of energy for the brain during prolonged starvation would come from: A. Ketone bodies C. Fatty acids B. Glucose D. Proteins Reference: Champe, P. C., t. al., Biochemistry, 2nd ed., p. 294. 83. In the overall scheme of human metabolism, which organ plays the most important role in caloric homeostasis? A. Brain C. Liver B. Kidney D. Muscle Reference: Champe, P. C., et. al., Biochemistry, 2nd ed., p. 283, 292. 84. In the well-fed state, the following molecules are stored XCEPT: A. Carbohydrates C. Fats B. Proteins D. Ketone bodies Reference: Champe, P. C., et. al., Biochemistry, 2nd ed., pp. 282-289. 85. Survival is possible in starvation because: A. The liver synthesizes glucose from non-carbohydrate sources. B. The brain uses glucose as energy source. C. The muscle proteins are not being continuously broken down for energy source. D. The fats are spared from degradation. Reference: Champe, P. C., et. al., Biochemistry, 2nd ed., pp. 292-294. 86. The high glucagon/insulin ratio seen in starvation: A. promotes mobilization of fatty acids from the adipose tissues. B. stimulates β-oxidation by inhibiting the production of malonyl CoA. C. leads to increased concentration of ketone bodies in the blood. D. All of the above. Reference: Devlin, F. M., Textbook of Biochemistry with Clinical Correlations, 5th ed., p. 724. 87. In the early refed state: A. the fatty acid concentration in the blood rises. B. liver glycogenolysis continues to maintain blood glucose levels. C. liver replenishes its glycogen by synthesis of glucose 6-phophate from lactate. D. glucose being absorbed from the gut is used primarily for fatty acid synthesis by the liver. Reference: Devlin, F. M., Textbook of Biochemistry with Clinical Correlations, 5th ed., p. 726. 88. Increased formation of ketone bodies during starvation is due to: A. increased levels of circulating glucagons. B. decreased formation of acetyl CoA in the liver. C. increased levels of free fatty acids in the serum. D. inhibition of β-oxidation of fatty acids in the liver. Reference: Champe, P. C., et. al. Biochemistry, 2nd ed., p.302. 89. Which of the following is the most important source of blood glucose during the last hours of a 48-hour fast? A. Muscle glycogen C. Liver glycogen B. Acetoacetate D. Amino acids Reference: Champe, P. C., et. al., Biochemistry, 2nd ed., p. 302. 90. The major cell membrane lipids are: A. Phospholipids C. Lipoproteins B. Cholesterol D. Fatty acids Reference: Murray, R. K., et. al., Illustrated Biochemistry, 26th ed., pp. 416-417. 91. The fluid mosaic model of biologic membranes states that: A. there is regularity in the distribution of the proteins within a monolayer. B. the membranes are symmetrical all throughout. C. membranes are lipid bilayers, ach with characteristic compliment of integral and peripheral proteins. D. oligosaccharide chains are found in the cytoplasmic side of the membrane. Reference: Murray, R. K., et. al., Illustrated Biochemistry, 26th ed., p. 92. The lysis of a fibrin clot: A. is in equilibrium with the formation of a clot. B. begins when plasmin binds to the clot. C. requires the hydrolysis of plasminogen into heavy and light chains. D. requires the conversion of plasminogen to plasmin by tissue plasminogen activator. Reference: Devlin, F. M., Textbook of Biochemistry with Clinical Correlations, 5th ed., p. 1051. 93. Lead poisoning would be expected to result in an elevated level of: A. Amonilevulinic acid C. Protoporphyrin I B. Phorphobilinogen D. Hemin Reference: Devlin, F. M., Textbook of Biochemistry with Clinical Correlations, 5th ed., p.1077. 94. The cell membrane component that prevents the crystallization or coming together of two fatty acid tails is: A. Phosphoglycerides C. Glycolipids B. Cholesterol D. Galactolipids Reference: Murray, R. K., et. al., Illustrated Biochemistry, 26th ed., p. 417. 95. Which is NOT an effect of erythropoietin? A. increased RBC count C. increased oxygen delivery to the tissues B. increased hemoglobin levels D. increased aldosterone secretion Reference: Campbell, M. K., Biochemistry, 3rd ed., p. 358. 96. Parathyroid hormone is a hypercalcemic hormone because it increases: A. intestinal absorption of calcium. C. mobilization of calcium from the bones. B. renal reabsorption of calcium. D. All of the above Reference: Champe, P. C., Harvey, R. A., Biochemistry, 2nd ed., p. 310 97. The lipoxygenase pathway of unsaturated fatty acids directs to the formation of: A. Prostaglandins C. Thromboxanes B. Leukotrienes D. Prostacyclins Reference: Champe, P. C., Harve, R. A., Biochemistry, 2 nd ed., p 187. 98. Which is NOT a function of cholesterol? A. Synthesis of cell membranes. C. Precursor of steroid hormones. B. Synthesis of Vitamin A. D. Precursor of bile salts. Reference: Murray, R. K., et. al., Illustrated Biochemistry, 26th ed., p. 219. 99. Megaloblastic anemia is caused by lack of: A. Panthothenic acid C. Pyridoxine B. Folic acid D. Ascorbic acid Reference: Champe, P. C., Harvey, R. A., Biochemistry, 2 nd ed., p. 326. 100. A smoker who complains of soft swollen gums and loose teeth is deficient in Vitamin C and therefore has impaired: A. hydroxylation of proline. B. hydroxylation of dopamine ß-hydroxylase. C. degradation of tyrosine. D. hydroxylation of bile acids. Reference: Champe, P. C., Harvey, R. A., Biochemistry, 2nd ed., p. 40. BIOCHEM BOARD REVIEW 0.25__A___ 1. A competitive inhibitor of an enzyme: A. increases Km without affecting V max B. decreases Km without affecting V max C. increases V max without affecting Km D. decreases V max without affecting Km 0.50___D__ 2. The Michaelis constant, Km is: A. numerically equal to ½ V max B. dependent on the enzyme concentration C. independent pH D. numerically equal to the substrate concentration that gives half-maximal velocity. 0.25__D___ 3. The rate of an enzyme-catalyzed reaction was measured using several substrate concentrations that were much lower the Km. The dependence of reaction velocity on substrate concentration can best be described as: A. independent of enzyme concentration B. a constant fraction of V max C. equal to Km D. proportional to the substrate concentration 0.50__D___ 4. Which of the following statements is NOT characteristic of allosteric enzymes? A. they frequently catalyze a committed step early in a metabolic pathway B. they are often composed of subunits C. they frequently show cooperativity for substrate binding D. they follow Michaelis-Menten kinetics 0.50__B___ 5. The presence of a non competitive inhibitor: A. leads to both an increase in the V max of a reaction and increase in the Km B. leads to a decrease in the observed V max C. leads to a decrease in Km and V max D. leads to an increase in Km without affecting V max Biochemistry 2nd edition lippincotts illustrated reviews (Pamela c. champe / Richard a. Harvey p 60-61 1.0__B___ 6. The property of an enzyme to catalyze a given chemical reaction is an intrinsic function of its: A. concentration C. amphoteric nature B. conformation D. electrophoretic mobility 0.50__A___ 7. The hyperbolic relationship between initial velocity and [S] concentration is described by the equation: A. v=Vmax [S]/ Km + [S] B. v=Km + [S]/Vmax [S] C. v=Km [S]/Vmax + [S] D. v=Vmax [S]/Km [S] 1.0__B___ 8. Plotting initial velocity against various pH values in an enzyme-catalyzed reaction gives: A. A hyperbolic curve B. A bell-shaped curve C. A linear plot D. A sigmoid curve 0.25__C___ 9. True of active site in enzyme, EXCEPT: A. it is the only site for catalysis B. it is the binding site for [S] C. its catalytic residues are sequentially arranged in relation to its primary structure. D. its shape generally complements the shape of the substrate A competitive inhibitor competes with the substrate to bind to it. 0.50__D___10. Isoenzymes are utilized as markers in the diagnosis of certain clinical conditions because: A. of their high catalytic activity B. of the unique combination of their subunits in forming the active polymeric especies C. they are present in significant concentration in specific cells D. they exhibit optimum activity within a very narrow pH range Biochemistry by harpers 0.25___C___11. TRUE regarding anomerism: A. Anomeric carbon for aldose, is Carbon 2 B. Anomeric carbon for ketose, is Carbon 1 C. In the alpha anomer the OH attached to the anomeric carbon is pointing to the right on Fischer’s structure and located downward in Haworth’s projection formula. D. All of the above 1.0__B____12. The chief constituent of fibrous part of plants, is: A. Starch B. Cellulose C. Chitin D. Peptidoglycan 0.25__C____13. Not true of osazone formation: A. There should be a free carbonyl group B. Mannose, fructose and glucose have the same osazone crystals C. This test could differentiate galactose from glucose D. Osazone crystals are soluble in strong alkali medium 0.50___D___14. Not true about a glycosidic bond: A. Acted upon by specific glucosidases B. May either be in L or D form C. Broken down by boiling with acids D. Is stable in an alkaline medium 0.50___A___15. D-glucose and L-glucose are stereoisomers; they are called as such due to; A. Their relationship to the D and L glycerose B. The conformation on their anomeric carbon C. The direction of optical activity D. All of the above 0.50___B___16. True regarding sucrose: A. It has a free carboxyl group B. It is a non-reducing sugar C. It is also known as sucrase D. All of the above 1.0___B___17. A sugar alcohol that is implicated in the causation of cataract in galactosemia, is A. Mannitol B. Galactitol\ C. Sorbitol D. All of the above 1.0___D___18. A keto sugar; A. Galactose B. Glucose C. Mannose D. Fructose 1.0___B___19.D-glucose and D-mannose are: A. Anomers of each other B. Epimers of each other C. Enantiomers of each other D. All of the above 1.0___D___20. Not true of Lactose: A. A reducing sugar B. Hydrolyzed by beta-glycosidase C. Not fermentable by yeast D. Has free carbonyl group at the galaxies moiety Introduction to Molecular Medicine: Choose the best answer: 0.5__C___21. Which technique can be use to analyze protein: A. Maxam-Gilbert B. Sanger’s method C. Western blot D. RFLP 0.5___A__22. Coding region in DNA A. Exon B. Intron C. probe D. primer 0.25___D__23. What is the key tool for recombinant DNA technology? A. DNA polymerase B. Topoisomerase C. Phosphatase D. restriction enzyme 0.75___C__24. What is the machinery for DNA cloning? A. Translation B. transcription C. Replication D. reverse transcription 0.25__A___25. What is the machinery for cloning cells? A. Cell cycle C. Meiosis B. mitosis D. DNA replication 0.5__B___26. Restriction enzymes are used by this organism to defend themselves. A. Viruses B. bacteria C. Fungi D. Mycoplasma 1.0__A___27. A blot technique that is involved in the analysis of DNA: A. Southern blot B. Northern blot C. Western blot D. Eastern blot 1.0__C___28. When cloning a DNA fragment with a length of 400,000 bp, the appropriate vector is: A. Plasmid B. Lambda C. Cosmid D. YAC B. 0.5__D___29. Which of the following enzyme is not required for the synthesis of cDNA ? A. reverse transcriptase B. Rnase H C. DNA ligase D. Dnase 1 0.25__A___30. What method is based on the preparation of large arrays of oligonucleotides on miniaturized solid supports for analysis of DNA sequence? A. DNA chips(microarray) B. RFLP C. Southern blot D. PCR 1.0__D___31. Which of the following enzymes does not form phosphodiester bonds? A. DNA ligase B. DNA polymerase C. RNA polymerase D. Dnase 1 0.25__C___32. Which of the following features of the vector will allow screening for host cells that were transformed with the recombinant DNA construct? A. OriC sequence B. Promoter sequence C. Antibiotic resistance gene D. Restriction site Reference: 1. Harper’s Biochemistry 2. Molecular Biology of the Cell by Alberts Gene Expression: Choose the best answer: 0.5__B___33. The following are TRUE regarding DNA replication, EXCEPT: A. Semiconservative B. Unidirectional C. Continous synthesis of the leading strand D. Discontinous synthesis of the lagging strand 1.0__C___34. Replication involves which of the following: A. Peptide bond formation B. Synthesis of RNA C. Synthesis of a new DNA strand D. Synthesis of proteins 0.5___B__35. Which enzyme is involved in DNA repair: A. DNA polymerase III B. DNA polymerase I C. Taq polymerase D. DNA polymerase II 0.5__A___36. The supercoiling of DNA is relieved by the action of: A. topoisomerases B. helicases C. DNA ligase D. SSB 0.5__D___37. What anchors the mRNA to the 16S rRNA of the ribosome during translation? A. Kozak sequence B. Promoter C. Initiation codon D. Shine-dalgarno sequence 0.5__A___38. The initiation codon is found in the ____ in eukaryotes: A. Kozak sequence B. Shine-dalgarno sequence C. Promoter D. Enhancer 0.5__C___39. The termination signal for transcription involves: A. hairpin loop + poly-A-tract C. Both B. hairpin loop + Rho factor D. Neither C. 1.0___D__40. The termination of translation is signified by: A. ter regions C. tus B. rho factor D. stop codons 1.0__A___41. The main enzyme that removes the RNA primer during replication is the: A. DNA polymerase I C. DNA polymerase III B. DNA polymerase II D. RNA polymerase 1.0___B___ 42. Which part in the tRNA contains the invariant CCA and the binding site for amino acids? A. Anticodon arm C. V arm B. Acceptor arm D. TψC arm Reference:1. Harper’s Biochemistry 0.5__A___ 43. Factor(s) that prevent(s) alpha-helix formation in a protein: A. Presence of Proline B. Presence of adjacent Aspartic acid and Argenine in the chain C. Presence of adjacent Valine and Alanine in the chain D. All of the above ( ref.: Harper’s Illustrated Biochemistry,26th ed.pp.31-32) 0.5___C__ 44. This inborn error of metabolism is manifested by damage to the arterial walls, skeletal deformities and convulsive seizures: A. Hartnup disease C. Homocystinuria B. Cystathioninuria D. Cystinosis ( ref.: Biochemistry-Lippincott’s Illustrated Review’s 2nd ed.p528) 0.5____D__ 45. True regarding Phenylalanine: A. It is the source of the naturally occurring tranquilizer of the body B. It can be converted to Tyrosine thru decarboxylation C. It is the source of a hormone that is used to induce sleep D. It is the source of the pigment responsible for our complexion (ref: Principles of Biochemistry-Lehninger,Nelson 2nd ed.p.528) 0.5____B__ 46. Hydrogen bonding can exist between the R groups of: A. Glutamic acid and glutamine C. Serine and asparagines B. Cysteine and tyrosine D. Aspartic acid and Lysine (ref:Principles of Biochemistry-Lehninger,2nd ed. P162-163) 0.75___D___ 47. Inborn errors of urea synthesis manifested by hyperammonemia: A. deficiency of carbamoyl PO4 synthetase B. deficiency of argininosuccinase C. deficiency of ornithine transcarbamylase D. all of the above (ref: Txtbook of Biochemistry with Clinical Correlations-Devlin, 4th edition p445-457) 0.5___C___ 48. True regarding the urea cycle: A. The synthesis of citrulline takes place in the cytosol B. The second ammonia that is detoxified thru the cycle enters at the level of arginine C. Arginase is a major control enzyme of the pathway D. All of the above (ref: Harper’s Illustrated Biochemistry,26th ed.pp245-247) 0.75___A___ 49. Regarding the levels of protein structure: A. The primary structure is maintained by peptide bonds between amino acids B. The second structure is maintained by R to R interactions C. The tertiary structure is maintained by hydrogen bonding between peptide bonds D. The quarternary structure is exhibited by all proteins (ref: Harper’s Illustrated Biochemistry,26th ed. P31-35) 0.75___C-__ 50. Glycolysis , glycogenesis and lipogenesis are stimulated by this hormone: A. glucagons B. cortisol C. insulin D. epinephrine (ref:Harper’s Illustrated Biochemistry,26th ed,pp 155-157,160-162,178-179) 0.5___A___ 51. Interconversion of sugars in the HMP shunt is made possible thru this enzyme: A. transketolase C. Glucose-6-PO4 dehydrogenase B. aldolase D. Glucose-6-phosphatase (ref: Harper’s Illustrated Biochemistry,26th ed.pp 163-166) 1.0___B___ 52 It is an amphibolic pathway and regarded as the final common pathway of metabolism: A. Embden-Meyerhof pathway C. Glycogenesis B. Citric acid cycle D. Krebs-Henseleit cycle (ref: Harper’s illustrated Biochemistry , 26th ed ,pp130-135) 0.75___D___ 53. All of the following enzymes catalyze substrate level of phosphorylation, EXCEPT: A. succinate thiokinase C. phosphoglycerate kinase B. pyruvate kinase D. phosphofructokinase (ref: Biochemistry: Lippincott’s Illustrated Reviews , 2 nd ed.pp92-108) 0.25___C___ 54. The energy generation phase of glycolysis starts with this reaction: A. conversion of glucose to glucose-6-PO4 B. conversion of fructose to fructose-6-phosphate C. conversion of fructose-6-PO4 to DHAP and glycealdehyde-3-phosphate D. conversion of glyceraldehydes-3-phosphate to 1,3-diphosphoglycerate (ref: Harper’s Illustrated Biochemistry , 26th ed.pp136-143) 0.5___B___ 55. Complete oxidation of one mole of glucose using the malate aspartate shuttle will yield how many moles of ATP (NET): A. 40 B. 38 C. 36 D.24 E. 12 (ref: Harpers illustrated Biochemistry,26th ed. Pp142-143) 0.75___C__ 56. This cycle recycles lactate formed in the muscles back to glucose in the liver: A. Anaerobic glycolysis C. Cori cycle B. Uronic acid pathway D. Glucose-alanine cycle (ref: Harper’s Illustrated Biochemistry,26th ed.p159) 0.75___D___ 57. True regarding Vitamin B12: A. It is only found in animal sources B. Deficiency develops if a person undergoes total gastroectomy C. It cannot be given in large doses for long periods of time because it causes toxicity D. All statements are correct ( ref: Harper’s Illustrated Biochemistry,26th ed. pp 491-492) 0.5___A___ 58. Function of Vitamin C: A. regulates cholesterol metabolism by promoting its excretion B. Prevents infection by strengthening the barrier that prevents the entry of microorganism C. Prevents destruction of carotenes and vitamin A D. Increase absorption of calcium and phosphorous in the small intestines ( ref: Harper’s Illustrated Biochemistry,26th ed.pp495-496) 0.75__B____ 59. True regarding Vitamin D: A. its activation involves a 2 step reduction process B. it can be synthesized from cholesterol in the presence of sunlight C. deficiency can cause keratomalacia D. its most active form is synthesized in the liver (ref: Harper’s Illustrated Biochemistry,26th ed.pp 484-485) 0.5___C___ 60. Function(s) of Vitamin B6; A. co-enzyme in the rate-limiting step of the Kreb’s cycle B. coenzyme in the committed step of glycolysis C. coenzyme in heme synthesis D. all of the above (ref: Harper’s illustrated Biochemistry,26th ed.p491) 0.5___B___ 61. Pantothetic acid is an energy-releasing vitamin because: A. it is involved in glycolysis B. it is involved in the Kreb’s cycle C. it is involved in steroid hormone synthesis D. it is involved in the HMP shunt (ref: Harper’s Illustrated Biochemistry,26th ed. p495) 1.0___A_____ 62. People who are fond of eating raw fish, raw clams and oysters may develop deficiency of this vitamin: A. Thiamine B. Riboflavin C. Niacin D. Pyridoxine ( ref: textbook of Biochemistry with Clinical Correlations-Devlin 4th ed. pp 1118-1120) 0.50___B____ 63. Which of the following acts as surface antigens? A. prostaglandins B. glycoshingolipids C. dolichols D. lecithin 0.50____A___ 64. Which of the following acts as lung surfactant? A. phosphatidylcholine B. phosphatidylinositol C. phosphatidylserine D. phosphatidylethanolamine 0.75___A____ 65. Which of the following is/are omega-6 fatty acids? A. linoleic acid B. docosahexaenoic acid C. eicosapentaenoic acid (EPA) D. linolenic acid 0.50____B___ 66. Which of the following is/are lipid components of all biological membranes? A. free fatty acid B. cholesterol C. triglyceride D. ganglioside 0.25___A____ 67. Which of the following fatty acids would exhibit the lowest melting temperature? A. Linolenic acid B. Linoleic acid C. Oleic acid D. Palmitic acid 0.50____C___ 68. Structural characteristics of the sphingomyelins include: A. ceramide and sphingosine B. sphingosine, ethanolamine and phsphatidic acid C. ceramide and phosphorylcholine D. sphingosine and phosphorylserine 0.50_____B___ 69. Lipoprotein density is directly proportional to its: A. cholesterol content B. protein content C. TAG content D. Phospholipid content 0.50____D_____ 70. The enzyme that hydrolyzes TAG in VLDL and chylomicra is: A. hormone-sensitive lipase B. pancreatic lipase C. gastric lipase D. lipoprotein lipase 0.75_____D____ 71. The cyclooxygenase pathway synthesizes: A. Prostaglandins B. Leukotrienes C. Thromboxanes D. A & C 0.75___D_____ 72. Ketone bodies are oxidized for ATP generation via: A. Beta-oxidation pathway B. Cyclooxygenase pathway C. Lipoxygenase pathway D. Kreb’s citric acid cycle 0.75____D____ 73. Ketonemia arising from the utilization of fat as the major alternative source of energy occurs in: A. diabetes mellitus B. starvation C. prolonged consumption of high fat diet D. all of the above 0.50____D____ 74. Glycerol phosphate, the backbone of TAG, is synthesized in the liver by: A. phosphorylation of glycerol by glycerol kinase B. phosphorylation of diacylglycerol C. reduction of dihydroxyacetone phosphate D. A & C are correct 0.75____C____ 75. True of the beta-oxidation of palmitic acid, EXCEPT: A. occurs in the matrix of mitochondria B. two oxidation steps generate 5 mols of ATP per cycle C. cleavage reaction occurs between the beta and gamma carbons D. the cell conserves 129 moles ATP per mole of palmitic acid 0.75____D____ 76. Utilizes ketone bodies for energy, EXCEPT: A. skeletal muscles B. brain C. cardiac muscles D. liver 1.00____B____ 77. The rate-limiting enzyme in the biosynthesis of cholesterol is: A. HMG-CoA oxidase B. HMG-CoA reductase C. HMG-CoA synthase D. HMG-CoA lyase 1.00___D_____ 78. Which of the following molecule is the largest energy reserve of the human body in terms of kilocalories? A. muscle glycogen B. muscle triglycerides C. liver glycogen D. adipose tissue triglycerides 0.75____D____ 79. Increased fatty acid oxidation occurs during, A. starvation B. diabetes mellitus C. diabetes insipidus D. A & B 0.50_____D___ 80. Ketone bodies, A. consist of acetoacetate, acetone, hydroxybutyrate B. are important fuels in extrahepatic tissues. C. are derived from fatty acids D. all of the above 0.50____D____ 81. Which of the following is/are true regarding VLDL? A. packaged in the liver cell B. hydrolysis of its TAG gives rise to LDL C. major vehicle of transport of endogenous TAG in Blood D. all of the above 0.25___B____ 82. Which of the following activates lipoprotein lipase? A. Apo E B. ApoCII C. Apo B D. None of the above 0.75___C___ 83. Glycolysis, glycogenesis and lipogenesis are stimulated by this hormone: A. glucagons B. cortisol C. insulin D. epinephrine 0.50___D___ 84. Effects of insulin: A. Mobilizes the glucose transporters from the Gogi apparatus to the cell membrane B. Stimulates pyruvate kinase and glucokinase C. Inhibits cyclic AMP D. All of the above 0.50___C___ 85. What is the second messenger of growth hormone? A. cyclic-AMP B. Ca/phosphoinositides C. Kinase/phosphatase cascade D. None of the above 0.75___A___ 86. Which of the following is/are cell associated recognition molecules? A. receptors B. hormones C. protein kinase D. none of the above 0.75___D___ 87. Hormones are synthesized, A. in one tissue transported to act on another organ B. by cells of epithelial origin C. by cells strategically located for a specific action D. all of the above 0.75___C___ 88. The following are hormone-related diseases EXCEPT, A. bronchial asthma B. grave’s disease C. pertussis D. myasthenia gravis 0.25___C___ 89. Which of the following is not a nanopeptide hormones? A. B. C. D. vasopressin oxytocin corticotropin none of the above 0.50___C___ 90. Cholera toxin causes ADP ribosylation of which subunit of G-proteins? A. gamma B. beta C. alpha D. none of the above 0.50___C___ 91. Which of the following is/are amino acid derived hormones? A. growth hormone B. parathyroid hormone C. thyroid hormone D. none of the above 0.75___B___ 92. Which of the following is/are released by nipple stimulation? A. vasopressin B. oxytocin C. neurophysin D. none of the above 0.75___B___ 93. Which of the following is a modified amino-acid hormones? A. growth hormone B. thyroid hormone C. parathyroid hormone D. none of the above 0.25___D___ 94. Which of the following is not a coupled system? A. CRH-ACTH-cortisol B. TRH-TSH-T3/T4 C. GnRH-LH/FSH-testosterone/estradiol/progesterone D. None of the above 0.50___B___ 95. Which of the following transport hormones from the hypothalamus through the axons to the posterior pituitary? A. endorphins B. neurophysins C. vasopressin D. none of the above 0.75___A____ 96. Which of the following is released by changes in serum osmolality? A. antidiuretic hormone B. parathyroid hormone C. oxytocin D. None of the above 0.75___C____ 97. Which of the following is released by nipple stimulation? A. vasopressin B. neurophysin C. oxytocin D. none of the above 0.50____C___98 The coupling of two iodinated tyrosyls form _____. A. tyrosine B. thyroglobulin C. iodothyronine D. none of the above 0.50____B___ 99. Which of the following forms of calcium is/are biologically active? A. complexed with organic acids B. ionized C. protein bound D. none of the above 0.25___A____ 100. Which of the following organs contain parathyroid hormone receptors? A. kidney B. muscle C. liver D. none of the above END OF EXAM !!! DEPARTMENT OF BIOCHEMISTRY MULTIPLE CHOICE : Choose the best answer. 90% MPL _ A_ 1. Referred to as “suicide bags” of the cell, containing a variety of hydrolytic and degradative enzyme – A. Lysosomes C. Microsome B. Golgi apparatus D. Ribosomes 0% _ B_ 2. The ability of water to absorb and store a large amount of heat thus preventing the rise in body temperature is called – A. High heat conductivity C. High latent heat of evaporation B. High specific heat D. All of the above 0% _ C__3. The most prominent feature of the eukaryotic cell, serving as its information center, is the – A. Mitochondria C. Nucleus B. Nucleolus D. Endoplasmic reticulum 0% __D_ 4. Reactions in vivo can be differentiated from reactions in vitro by the following – A. Mild due to high specific heat of water. B. Fast due to presence of enzymes. C. Orderly due to cell specialization. D. All of the above. 0% _ B_ 5. Water as hydrophilic colloid system, has for its main function – A. Hastens chemical reaction. B. Maintains body temperature. C. Maintenance for the size and shape of cell. D. All of the above. Susan is 21 years old. Ever since she can remember, her monthly menstrual periods has been associated with a moderate to severe crampy hypogastric pains, accompanied by a profuse flow. Her physician prescribed iron supplements to be taken everyday and referred her for a gynecologic consult. However, she is so busy in school that it seems impossible to fit this with her schedule. There are many occasions when she forgets to buy her iron tablets and, even when she has a supply of it, she forgets to take the medicine regularly. Lately she has been complaining of body weakness. On more than one occasion, her friends commented that she looked pale. 60% _ B_ 6. The following could be true about the peripheral smear of the blood of Susan. A. the rbc’s are unusually large (megaloblastic). B. the rbc’s are small (microcytic) and hypochromic. C. the rbc’s would have different sizes, and different shapes. D. All of the above are true. 70% _ A_ 7. In her case, the following results could be true: A. level of hemoglobin is below normal B. serum transferrin value is depressed. C. serum ferritin value is elevated D. All of the above are true. MULTIPLE CHOICE : Choose the best answer. MPL 0% _D_ 8. Therefore, the best thing that Susan could do is: A. Seek gynecological consult. B. Eat iron rich foods. C. Continue with her iron supplement. D. All of the above. 0% _ A_ 9. Iron in the body is absorbed in: A. ileum B. fundus of the stomach C. duodenum D. jejunum 0% _ D_ 10. The glycoprotein involved in the transport or iron is: A. ferredoxin C. ferrous iron B. apoferritin D. transferring 0% _ B_11. The major protein involved n the storage or iron is: A. lactoferrin C. transferrin B. ferritin D. ferredoxin 0% _A_ 12. Iron that has anti-microbial effects thus can protect the newborn: A. lactoferrin C. apoferritin B. ferredoxin D. transferrin 0% _B_ 13. The following statement(s) is/are true about iron: A. Cooking of food does not necessarily affect its absorption. B. Low ph is necessary in its absorption C. Much of it is absorbed in the intestines and much is also excreted. D. All of the above are true. 0% _D_ 14. Ingested iron is: A. Absorbed by the mucosal cell B. Once absorbed by the mucosal cell, it can be excreted through cellular slough. C. Absorbed, then it could be absorbed by the capillary and trapped by transferrin. D. All of the above are true. 0% _ B_ 15. Protein digestion starts in the: A. Mouth where the amylase can be found. B. Stomach where the acidic environment favors denaturation. C. Intestines where proteolytic enzymes are abundant D. All of the above. 0% _ D_ 16. The following statement(s) is/are true about protein turnover: A. Proteins that are important in metabolic regulation are generally short-lived B. Protein turnover takes place constantly in cells. C. Ubiquitin tap the protein for destruction D. All of the above. 0% __D_17. Amino acids released on protein digestion follow this fate: A. They are degraded into specific compounds B. The amino group is removed form the amino acid in a process called deamination. C. The keto acids that results are metabolized so that the C skeletons can enter the TCA cycle. D. All of the above. 0% MULTIPLE CHOICE : Choose the best answer. MPL __A_ 18. Excess NH4 from the breakdown of amino acids are: A. converted into urea and excreted B. converted to proteins and re-utilized by the body C. utilized in the glycolytic pathway for glucose formation D. all of the above 0% __C_19. The carbon skeletons of the 5C amino acids enter the citric acid cycle as: A. glutamate C. Ketoglutarate B. glycine D. urocanate 0% _ A_ 20. The amount of enzyme that will produced one micromote of product/min. at 250C, under standardized condition is called – A. unit of activity C. turnover number B. specific activity D. Michaelis-Menten constant 0% _ B_ 21. When lead combines with the sulfhydryl group of enzymes, it inactivates the enzyme; this inactivation is brought about by – A. competitive inhibition B. non-competitive inhibition C. allosteric inhibition D. de-inhibition 0% _B_ 22. In a complex enzyme system, the protein, heat labile, non dialyzable portion is called – A. Holoenzyme C. Co-enzyme B. Apoprotein D. Prosthetic group 0% _B_ 23. Activity of enzymes is expressed in terms of – A. product formation C. ES complex B. velocity D. Km 0% _D_ 24. At the start of the reaction of enzymes, velocity of enzyme reaction is directly proportional to enzyme concentration provided the following condition(s) is/are present – A. substrate is in excess C. a 1st order kinetics B. a zero order kinetics D. A and B 0% _C_ 25. In an enzyme-substrate reaction, a large Km means – A. it is equal to its maximum velocity B. a high affinity of enzyme for the substrate C. a low affinity of enzyme for the substrate D. it is directly proportional to its velocity 0% _A_ 26. A co-enzyme that can act alternately as an oxidizing and reducing agent is – A. Vitamin C C. Vitamin B2 B. Vitamin B1 D. Vitamin K 0% _A_ 27. The following enzyme can bring about the cleavage of C-C, C-O, and C-N bonds in a substrate – A. Lyase C. Isomerase B. Ligase D. Hydrase 0% MULTIPLE CHOICE : Choose the best answer. MPL _B_ 28. An enzyme is considered as oxidase, when in the reaction which it catalyzes: A. oxygen is added to the substrate B. oxygen is the H+ acceptor C. oxygen acts as co-enzyme D. oxygen is given off 0% _B_ 29. The amount of energy expressed in calories per mole, that must be supplied before there is sufficient interaction between reactants to form product, is called – A. unit of activity C. catalytic energy B. energy of activity D. Km 0% _A_ 30. A 2 month old bottle-fed infant was brought to her pediatrician’s clinic because the mother complained that the infant often had colic and diarrhea which were especially noted after intake of her formula. This infant could be deficient in: A. Lactase C. Amylase B. Maltase D. Sucrase 0% _A_ 31. Initial chemical digestion of carbohydrates to maltose takes place in the: A. Mouth C. Stomach B. Esophagus D. Intestine 0% _D_ 32. Acetylcholine stimulates the secretion of the following, EXCEPT; A. Saliva C. Pancreatic enzymes B. Gastric juices D. No exception 0% _C_ 33. The following statements describe the plasma membranes of the parietal cells in the stomach: A. The contaluminal region contains H+/K+ ATPase. B. Chloride ions are exchanged for HCO3 ions in the luminal side. C. Under steady state conditions, movement of HCI through the luminal region is coupled to the movement of bicarbonate ions through the contraluminal side. D. None of the above. 0% _C_34. A 40 year old, G2P2, Filipina, weighing 80 kgs. Came into the emergency room complaining of severe RUQ pain radiating to the back which was noted after eating lechon at her friend’s birthday party. The internist’s diagnosis which was confirmed by ultrasound was cholecystitis with cholithiasis. The reasons why gallstones develop in the gallbladder are the following, EXCEPT: A. Contact time between bile and crystallization nuclei is greater in the gallbladder. B. Gallbladder concentrates bile by reabsorbing water C. Bile secreted by the gallbladder is supersaturated with cholesterol than the bile secreted by the liver which contains more phospholipids. D. No exception. 0% MULTIPLE CHOICE : Choose the best answer. MPL D_ 35. True of micelles, EXCEPT: A. Aggregates of bile acids which possess detergent properties. B. Major vehicle for moving lipids from the lumen to the mucosal surface of the enterocytes where absorption occur. C. Not important in the absorption of fat soluble vitamins. D. No exception. 0% _B_ 36. The following statement(s) about pepsin is/are true: A. They denature proteins making them more susceptible to hydrolysis by amylases. B. They are active in an acid environment but unstable in a neutral environment. C. They are generated from the proenzyme pepsinogen which are activated by HCl alone. D. All 0% _B_ 37. Glucose transport through the intestinal epithelium: A. Occurs through tight junctions between cells through a Na+-glucose cotransport. B. Occurs transcellularly driven by the electrochemical Na+ gradient C. Is directly dependent on a supply of ATP that energizes the Na+-K+ATPase. D. Occurs with the concentration gradient. 0% _C_ 38. The final digestion of proteins occurs at: A. B. C. D. The intestinal lumen by trypsin The luminal surface of the enterocytes by aminopeptidases Inside the enterocytes by dipepetidases. In the capillaries located near the bases of the enterocytes 0% _A_ 39. Absorption of lipids by the epithelial cells occurs by: A. Diffusion through the plasma membrane B. Active transport C. Cotransport with Na+ D. Carrier mediation 0% _B_ 40. The principle behind the use of oral rehydration in diarrhea is the theory of ”itching on” the ff. mechanism: A. Sodium chloride coupled entry B. Sodium-glucose coupled entry C. Passive diffusion of sodium D. All of the above 0% _D_ 41. Studies have shown that inspite of the diarrhea considerable absorption in the GIT still occurs which is true for – A. Carbohydrates – 80%-90% C. Proteins – 50-75% B. Fats – 50-80% D. All of the above 0% _B_ 42. The signs and symptoms of dehydration usually are not obvious until fluid losses amount to at least – A. 1-2% of body weight C. 6-9% of body weight B. 4-5 of body weight D. 10-15% of body weight 0% MULTIPLE CHOICE : Choose the best answer. MPL _B_ 43. To achieve maximal absorption of Na+ and water, the ORS solution should have a glucose concentration of – A. 10-20 gm/L C. 30-40 gm / L B. 20-30 gm/L D. 40-50 gm/ L 0% _C_ 44. The leading cause of diarrhea (etiologic agent) in children below 5 years old is – A. Staph. aureus C. Rotavirus B. E. coli D. Cholera vibrio 0% _D_ 45. The following are true regarding inorganic elements, EXCEPT: A. They are needed to provide a suitable medium for protoplasmic activity. B. They play a role in osmotic phenomena. C. They are involved in acid-base equilibra. D. They are negligible and are not important in the body metabolism 0% _B_ 46. The freely moving calcium in tissue, extracellular fluid and blood is known as: A. Ionized calcium C. Bound-calcium B. Miscible calcium pool D. All of the above 0% _B_ 47. The vitamin that aids the absorption of calcium and phosphates in the GIT: A. Vitamin A C. Vitamin E B. Vitamin D D. Vitamin K 0% _C_ 48. Iron in the diet is reduced to the ferrous form in the presence of: A. Ferritin C. Gastric acidity B. Antacids D. Calcium 0% _B_ 49. Extrahepatic tissues like the skeleton and heart muscle utilize the following ketone bodies as source of fuel, EXCEPT: A. Acetoacetic acid C. B-hydroxybutyric acid B. Acetone D. Ketoacids 0% _D_ 50. Chylomicrons produces the “milky” appearance of blood following a heavy intake of fat, and can be removed only by the action of – A. Lipoprotein lipase C. Insulin B. Heparin D. A and B 0% _D_ 51. After long period of starvation, fats may still be found in the tissues, in the form of – A. Triglycerides C. Cholesterol B. Phospholipids D. B and C 0% _D_ 52. Fatty acids, in order to be oxidized through B-oxidation in the mitochondria must be”ferried” through the mitochondrial membrane and this is brought about by – A. Acetyl Co A C. Thiokinase B. Thiolases D. Carnithine 0% 0% 0% _D_ 53. Once formed in the body, cholesterol can give rise to – A. Bile acids C. Steroid hormones B. Vitamin D D. All of the above MULTIPLE CHOICE : Choose the best answer. MPL _A_ 54. The following statement(s) is/are true about glycolysis: A. It can occur without oxygen. B. It happens in the mitochondria of cells. C. It is only an alternative pathway for the metabolism of glucose. D. Aerobic glycolysis results in the production of lactic acid _C_ 55. Storage form of glucose in animals: A. Starch B. Polysaccharides C. Glycogen D. All of the above 0% _A_ 56. Gluconeogenesis is the process of: A. Transormation of non-glucose substrates into glucose. B. Breakdwon of glycogen into single glucose units. C. Breaking of glucose into energy. D. All of the above. 0% _A_ 57. Glycogenolysis means: A. Breakdown of glycogen into single glucose units. B. Breakdown of glucose into energy. C. Formation of glycogen from single glucose units. D. All of the above. 0% _C_ 58. The end product of anaerobic metabolism is; A. Pyruvate B. Glyceraldehyde 3 phosphate C. Lactate D. 2 phosphoglycerate Wilma, a black, silky-skinned, long-legged sexy model was interviewed over at a TV talk-show and was asked about her features which were very much different form her claimed parents and sibling. Someone from out-ofthe blue called and claimed to be her biological father. To settle this big controversy about her identity she had to submit herself to a DNA test. 0% _A_ 59. Only 4 bases in DNA can code for the huge amount of information needed to make an organism and this is because of the ff. reason(s): A. The linear oder or sequence of bases along the DNA is completely unrestricted. B. Base pairs lie almost flat and staked on top of the another perpendicular to the long axis of the double helix. C. Base pairings in the double helix are said to be complementary. D. DNA bases are arranged into codons in different combinations and in various lengths. 0% _D_ 60. The ff. is/are correct of the nomenclature of nucleotides: A. They are named as the phosphates of nucleosides. B. The phosphorus atoms are labeled , and gamma starting from that nearest to the C5. C. The primed number indicates the position of esterification on ribose. D. All of the above. 0% MULTIPLE CHOICE : Choose the best answer. MPL _D_ 61. Physiologic functions of nucleotides include: A. Protein and nucleic acid synthesis B. Regulatory cascades C. Intra and intercellular signal transduction pathways D. All of the above 0% _B_ 62. The initial step is the salvage pathway for the recovery of the purines and pyrimidines released during metabolism involves the following: A. Phosphorylation of inosine monophosphate to inosine diphosphate B. Reaction of ribose-5-PO4 with phosphoribosyl pyrophosphate (PRPP) to form the monophosphate. C. inosine monophosphate is dephosphorylated to form hypoxanthineribonucleoside. D. inosine monophosphate is aminated to form inosine. 0% _C_ 63. Base pairing in the DNA helix is complementary, this means that; A. Adenine pairs with cystosine B. Thymine pairs with guanine C. Guanine pairs with cytosine D. Thymine pairs with cytosine 0% _D_ 64. The base pairs are the right size to fit into the helix because: A. A-C of G-T pairs have the correct H-bonding pattern. B. The distance between the points at attachment of the bases to the 2 strands of the sugar PO4 backbone is the same for the 2 pairs. C. The length of one complete turn of the helix contains 10 base pairs. D. All of the above. 0% _D_ 65. Denaturation of DNA: A. is also referred to as “melting” B. is characterized by hyperchromicity C. is seen when bases become unstacked D. all of the above 0% _D_ 66. The foremost utility of DNA denaturation: A. to determine genetic sequence in gene mapping B. to obtain single stranded DNAs C. for experimental purposes of any kind D. all of the above 0% _B_ 67. Ben was diagnosed to have chronic myelocytic leukemia. He is on the second cycle of his C hemotherapy. After the session, he was given a prescription for allopurinol tablets. The reason for this Is: A. he has an increased excretion of uric acid B. there is an increased breakdown of nucleic acids C. leukemic patients synthesize purines and pyrimidines faster D. one of the complication of leukemia is gouty arthritis 0% ntrails. _D_ 68. Being his birthday, David had an alcohol binge last night indulging himself with chicken liver and 0% He woke up with a splitting headache, and acute pain on his left big toe and he was dizzy. The big toe seems very swollen. David is probably having; A. a hangover C. rheumatoid arthritis B. osteoarthritis D. acute gouty arthritis MULTIPLE CHOICE : Choose the best answer. MPL _D_ 69. Primary management in David’s case would be: A. hydration B. pain relievers C. minimize intake of purine rich food D. all of the above 0% _B_ 70. As to the latest concept of respiratory chain (ETS) it is observed that the collecting point for reducing substrate is: A. NAD linked dehydrogenase. B. Coenzyme Q. C. FAD linked DEH (dehydrogenase). D. Electron transferring flavoprotein. 0% _B_ 71. The enzyme present in RBC that catalyzes the destruction of hydrogen peroxide thus protecting the membrane lipids and hemoglobin against oxidation by peroxide is – A. Catalase C. Monooxygenase B. Glutathione peroxidase D. Superoxide dismutase 0% _A_ 72. Some biochemist believed that the toxicity of oxygen is due to its conversion to superoxide and this is formed – A. during univalent oxidations with molecular oxygen in the respiratory chain. B. when reduced NADP are reoxidized univalently by molecular oxygen. C. when reduced cytochromes are oxidized. D. All of the above. 0% _D_ 73. In the TCA cycle, FAD is the hydrogen acceptor form the following compounds, thus forming 3 ATPs – A. Isocitrate C. L-malate B. , Ketoglutarate D. All of the above 0% _A_ 74. Atractyloside inhibits oxidative phosphorylation by – A. Inhibiting the oxidation of the substrate that communicates directly with the respiratory chain. B. Inhibiting the transport of ADP into the mitochondria. C. Blocking the respiratory chain at cytochrome oxidase. D. Blocking the breakdown of ATP to c-AMP. 0% _C_ 75. Evaporation through the skin and lungs as a vehicle for losing heat from the body, removes – A. 5% of heat C. 27% of heat B. 10% of heat D. 70% of heat 0% _B_ 76. The ability of the different foodstuffs to replace each other in the diet for energy as well as for heat production in proportion to their caloric value is – A. Specific dynamic action of foods B. Isodynamic laws of Hubner. C. Protein sparing action of foods. D. Plethora Theory of Lusk 0% MULTIPLE CHOICE : Choose the best answer. MPL _D_ 77. The Atwater-Rosa-Benedict calorimeter is used to measure the following – A. heat produced C. carbon dioxide output B. oxygen utilized D. core temperature 0% _D_ 78. When the temperature of the environment is high, one way of losing heat from the body is through the skin via the process of – A. radiation C. conduction B. convection D. All of the above. % _C_ 79. A 27 year old female came to the ER for complaints of difficulty of breathing increase after a quarrel with her boyfriend. All vital signs were normal except for an increase in the respiratory rate of 30/min. Her digits were slightly cool and hyperextended. An ABG was taken and the result showed respiratory alkalosis. The mechanism of the respiratory alkalosis in this state is the following – A. The low oxygen content of the air stimulates respiration which cause excess loss of CO 2 and development of mild respiratory alkalosis upon ascent to high altitude. B. Major means of compensation are the chemical buffers of the body fluids and the ability of the kidney to increase bicarbonate secretion. C. Overventilation of the lungs causes an excess removal of CO 2 from the body. D. All of the above are true. 0% _A_ 80. A 2 year old male child was brought to the ER by the mother because of unresponsiveness. The patient had on and off episodes of diarrhea 1 week PTA which the mother cannot account. 3 days PTA, she noted the child to have increased episodes of stooling, but still not quantified and gave the child, boiled rice water which she claimed had reduced the diarrheic episodes. A nite PTA, the patient kept on sleeping and this morning when patient was awakened by the mother, he was unresponsive. BP = 40/20 ; CR = 92/MIN ; RR = 12/min shallow; Temp. = 36.50C. Skin showed (+) testing, oral cavity dry, clear breath sounds, regular cardiac rhythm, no murmur, abdomen was tympanitic. Serum electrolytes showed Na = 128 meq/L ; K+ = 2.5 meq/L ; ABG pH 7.3 ; pCO2 = 45 ; HCO3 = 15 ; O2 saturation = 95%. Which of the following is most likely the problem in this patient? A. The patient developed metabolic acidosis because of severe Dehydration 20 to diarrhea. B. The patient went into coma because of brain damage. C. The patient is very weak because of hypokalemia alone. D. The patient is just tired from having diarrhea and needs to sleep it off. 0% _B_ 81. The mechanism for the above impression is due to: A. Impairment of renal tubular bicarbonate reabsorption causing the loss of HCO 3- in the urine. B. Normally, gastrointestinal secretions contain large amounts of HCO 3- and they are lost in the stools during diarrheic episodes. C. Fats in the GIT are split into acetoacetic acid casuing severe metabolic acidosis. D. The kidneys of this patient did not have a compensatory mechanism. 0% 0% MULTIPLE CHOICE : Choose the best answer. MPL _A_ 82. The following are the abnormalities seen in the patient, EXCEPT: A. Hypoxemia C. Hyponatremia B. Hypokalemia D. Severe dehydration _D_ 83. Other causes that could contribute to metabolic acidosis include the following – A. chronic renal failure C. vomiting B. ingestion of aspirin D. all of the above 0% 0% _D_ 84. The following statement(s) characterize(s) the hormonal cascade system: A. The target gland is the last hormone producing tissue in the cascade which is stimulated by a specific anterior pituitary hormone. B. Signals consisting of external and internal hormonal signals are first transmitted to the CNS. C. Negative feedback mechanisms provide tight controls in the operation of the cascade. D. All of the above. _A_ 85. A 14 year old female was admitted for multiple injuries secondary to a vehicular accident. A CT scan was done which showed a fracture in the sella turcica and a hemorrhage at the posterior ituitary, the anterior pituitary was intact. The injury would cause failure in the ultimate release of which hormone: A. Oxytocin C. Thyroid stimulating hormone B. Growth hormone D. Prolactin 0% _A_ 86. Symptoms of the abovementioned hormone deficiency would include: A. Failure of milk letdown B. Growth delay C. Easy fatigability D. Inability of the breast tissue to produce milk 0% _A_ 87. A 26 year old male, figured in a car accident. Physical examination showed bleeding on multiple sites with BP noted to be 90/60mmHg. What is the main driving force for aldosterone synthesis: A. Angiotensin II C. Stress B. Acetylcholine D. All of the above 0% _A_ 88. The following statement about corticosteroid-binding globulin is true: A. It binds about 80% of the total 17-hydroxysteroids in the blood. B. 22% of cortisol in the blood is bound to corticosteroid-binding globulin. C. Majority of aldosterone is bound to corticosteroid-binding globulin. D. Hormones bound to corticosteroid-binding globulin bind to intracellular receptors and produce biological effects. 0% _C_ 89. Hormones bind to specific receptors sites in the cell. Which is not the right pair: 0% A. Insulin : Cell surface B. Cortisol : Cell cytoplasm C. Aldosterone : Cell surface D. Thyroid hormone : Nucleus MULTIPLE CHOICE : Choose the best answer. MPL _D_ 90. “Hormone” is a Greek term which means: A. to regulate B. to control C. to overpower D. to set in motion 0% _A_ 91. An understanding of the circulating half-life of a hormone is important to: A. achieve physiologic hormone replacement B. have an idea on how the hormone is synthesized C. get a general view on the secretion of the hormone D. facilitate understanding on how the hormone is degraded 0% _A_ 92. Hormones bind to receptors with: A. highs specificity B. high affinity C. no regard to the class of the receptor D. only A and B 0% _A_ 93. True about the negative feedback mechanism: A. Conditions resulting from the action of the hormone prevents its further release. B. It usually potentiates the activity of the hormone itself. C. When the target tissue activity rises to a certain level, feedback signals empower the hormone even more to produce a cascade of effects. D. The controlled variable is the secretory rate of the hormone. 0% _B_ 94. One of the following hormones uses the cAMP as the second messenger system: A. Glucagon C. Vasopressin B. Thyroid releasing hormone D. Angiotensin II 0% _C_ 95. One of the following hormones use the phospholipase C as the second messenger system: A. Calcitonin B. B receptors of the catecholamines C. Alpha receptors of the catecholamines D. Follicle stimulating hormone. 0% 0% 0% 0% 0% _A_ 96. True about the positive feedback mechanism: A. The biological action of the hormone causes additional secretion of the hormone. B. The surge of the hormone causes inhibition to its further release. C. It prevents the overactivity of the hormone system D. A fitting example would be the hypothalamic, pituitary thyroid axis. Jessica visited her physician a week ago for urinary tract infection. She was given a course of antibiotics which relieved her symptoms. One of the incidental findings in her urinalrysis was a sugar of +2. Her 2 babies were both born big and fat. She herself is on the obese side. _A_ 97. The abnormality in the glucose homeostasis in Jessica’s case could be due to a derangement in the hormones produced by the following organs, EXCEPT: A. kidneys C. pancreas B. thyroid gland D. adrenals MULTIPLE CHOICE : Choose the best answer. MPL _D_ 98. If Jessica’s pancreas is normal, the following would describe the organ anatomically: A. It would be retroperitoneal at the level of the 4th and 5th lumbar verterbrae. B. Anterior to it would be the transverse colon, the attachment of the transverse mesocolon and the stomach. C. Posterior to it would be the lesser sac. D. All of the above. _D_ 99. Insulin has the following effect(s): A. inhibition of lipoprotein lipase B. increased glycogen synthesis C. decreased K+ uptake D. All of the above _C_ 100. Insulin acts rapidly by: A. inhibiting protein catabolism B. inhibiting protein synthesis C. increasing transport of glucose D. activating phosphorylase and gluconeogenic enzymes. BIOCHEMISTRY REFERENCES : 1. Biochemistry – Campbell 3rd edition 2. Textbook of Biochemistry with Clinical Correlation by Thomas Devlin 3. Biochemistry by Harper, 25th edition 4. Biochemistry a Case Oriented Aprroach by Mosby 5. Biochemistry by Orten and Newhaus LIPID CHEMISTRY / LIPID METABOLISM OBJECTIVE: A. The students must be able to describe the chemical nature and properties of the different types of lipids and relate them to their cellular functions B. The students must understand the biosynthesis and catabolism of the commonly occurring lipid in human cells and explain the biochemical basis of diseases associated with abnormalities in lipid transport and metabolism 1. Of the following lipoproteins, which one is inversely related to the incidence of coronary atherosclerosis? a. chylomicron b. high density lipoprotein c. intermediate lipoprotein d. low density lipoprotein e. very low density lipoprotein ( HARPER’s 25th ch 27 pp 268-271) 2. . In the shuttle of mitochondrial acetyl coenzyme A to the cytosol for fatty acid synthesis, in which step generates NADPH? a. oxaloacetate + acetyl coenzyme A citrate b. oxaloacetate malate c. malate pyruvate d. pyruvate oxaloacetate e. citrate - coenzyme A oxaloacetate - acetyl coenzyme A ( Harper’s ch 24 pp238-239) 3. The lipoprotein that serves to transport triacylglycerol from the liver to the different extrahepatic tissues: a. chylomicrons b. high density lipoproteins c. intermediate density lipoproteins d. low density lipoproteins e. very low density lipoproteins (Harper’s Ch 27 p 268-271) 4. . Which of the following apolipoproteins serves as inhibitor of lecithin:cholesterol acyltransferase (LCAT)? a. apolipoprotein A-II b. apolipoprotein A-IV c. apolipoprotein B-48 d. apolipoprotein C-I e. apolipoprotein C-II ( Harper’s ch 27 pp 270-271) 5. . In the following steps in ketone bodies metabolism, NADH is generated in: a. acetoacetate acetone b. acetoacetate beta hydroxybutyrate c. acetoacetyl coenzyme A + acetyl coenzyme A HMG coenzyme A d. beta hydroxybutyrate acetoacetate e. HMG coenzyme A acetoacetate + acetyl coenzyme A ( Harper’s ch 24 p 244-245) 6. Human body synthesize cholesterol de novo from acetyl coenzyme A. Cholesterol synthesis occurs in which of the following organelles? a. cytosol b. endoplasmic reticulum c. golgi apparatus d. mitochondria e. ribosomes ( Harper’s ch 28 p285) 7. . Among the following apolipoproteins, which one serves as lipid transfer protein? a. apolipoprotein A-IV b. apolipoprotein B-100 c. apolipoprotein C-III d. apolipoprotein D e. apolipoprotein E ( Harper’s ch 27 p 271) 8. Among the following conditions, which one is characterized by pathologic accumulation of galactocerebroside in the affected tissues. a. Farber's Disease b. Fabry's Disease c. Gaucher's Disease d. Krabbe's Disease e. Metachromatic Leukodystrophy ( Harper’s ch 27 p 267t) 9. . Which of the lipoproteins has the highest triacylglycerol content? a. chylomicrons b. high density lipoproteins c. intermediate density lipoproteins d. low density lipoproteins e. very low density lipoproteins (Harper’s Ch 27 p 268-271) 10. . Ketone bodies maybe synthesized from fatty acids by which of the following organs or cells? a. skeletal muscle b. liver c. kidney d. erythrocytes e. brain (Harper’s ch 24 p242) 11. Spontaneous decarboxylation of acetoacetate results in the formation of: a. acetone b. acetyl coenzyme A c. 3-hydroxybutyrate d. malonyl coenzyme A e. propionate ( Harper’s ch 24 p 242-243) 12. Which of the lipoproteins has the highest total lipid content? a. chylomicrons b. high density lipoproteins c. intermediate density lipoproteins d. low density lipoproteins e. very low density lipoproteins ( Harper’s p 268) 13. The major site of fatty acid synthesis: a. mammary gland b. liver c. kidney d. brain e. adipose tissue (Harper’s ch 23 p 230-231) 14. Of the following lipoproteins, which one is elevated in Type I Hyperlipidemia? a. chylomicrons b. high density lipoproteins c. intermediate density lipoproteins d. low density lipoproteins e. very low density lipoproteins (Harper’s Ch 27 p 268-271) 15. Of the following lipids, which one is accumulated is tissues of patient with Tay-Sach’s Disease? a. ceramide trihexoside b. galactocerebroside sulfate c. ganglioside d. glucoceberoside e. sphingomyelin (Harper’s p 267) 16. In the separation of plasma lipoprotein by electrophoresis on agarose gel, which fraction is located closest to the negative pole? a. chylomicrons b. HDL c. LDL d. VLDL e. Triglycerides (Harper’s Ch 27 p 268-271) 17. During uncontrolled diabetes mellitus or starvation, which of the following organs utilizes ketone bodies as much as 75% for its energy substrate? a. Heart b. Brain c. Kidney d. Skeletal muscles ( Harper’s ch 29 p 301) 18. In the biosynthesis of fatty acids, what is the compound that transports the acetate group out of the mitochondria into the cytoplasm a. pyruvate b. malate c. citrate d. acyl carnitine e. acyl coenzyme A (Harper’s ch 23 p 236) 19. Activation of medium chain and short fatty acids occurs in the a. Ribosomes b. Mitochondrial matrix c. Golgi apparatus d. Endoplasmic reticulum e. Cytosol (Harper’s pp 238-239) 20. The committed step in fatty acid synthesis is the formation of a. Acetyl coenzyme A b. Acetyl acyl carrier protein c. Malonyl coenzyme A d. Malonyl acyl carrier protein ( Harper’s Ch 23 pp 230) B. Carbohydtrate chemistry/ Carbohydrate metabolism OBJECTIVES: a) The student must be able to describe adequately the chemical properties of carbohydrates and relate them to their cellular function b) The students must describe the interrelationships between the various pathways of carbohydrate metabolism and explain the biochemical basis of diseases resulting from impairment of carbohydrate metabolism 1. a D glucose and a L glucose are a. Anomers b. Epimers c. Tautomers d. Enantiomers (Berg et al BIOCHEMISTRY 5TH ED p 296) 2. This sugar derivative is produced by the reduction of the carbonyl group on a monosaccaharide a. sorbitol b. glucoronic acid c. glycoside d. gluconic acid ( Harper’s Ch 15 p 153) 3. Of the following hexoses, which is a constituent of glycolipids and glycoproteins? a. glucose b. galactose c. fructose d. xylulose ( Harper’s ch 56 p 676-677) 4. Which of the following glycosaminoglycans are found in large amount in cartilages a. Dermatan sulfate b. Keratan sulfate c. Choindroitin sulfate d. Heparan sulfate e. Hyaluronic acid ( Harper’s Ch 57 p 704) 5. The compound that is the probable causative factor in the development of cataract in patients with diabetes mellitus a. Dulcitol b. Fructose 1-phosphate c. galactose 1-phosphate d. glucose 1-phosphate e. sorbitol ( Harper’s p 228-229) 6. The glycogen storage disease resulting from the deficiency of muscle phosphorylase a. Pompe’s disease b. McArdle’s disease c. Her’s disease d. Forbe’s disease e. Andersen’s disease (Harper’s ch 20 p 206t) 7. What is the major energy source for spermatozoa in seminal fluid? a. Fructose b. galactose c. glucose d. ketone bodies e. xylulose 8. A patient is diagnosed as having von Gierke’s disease is likely to exhibit which of the following clinical manifestations a. an enlarged liver b. hyperglycemia c. hypolipidemia d. hypouricemia (Harper’s Ch 36 p 397) 9. This enzyme is common to both glycolysis and gluconeogenesis a. Glyceraldehyde 3-phosphate dehydrogenase b. glucose 6-phosphatase c. pyruvate kinase d. pyruvate carboxylase (Harper’s p 194/211) 10. In humans, liver glycogen stores are adequate up to how many hours without support from gluconeogenesis? a. 4 hours b. 12 hours c. 24 hours d. 48 hours (Harper’s pp214-217) C. BIOENERGETICS and BIOLOGICAL OXIDATION OBJECTIVES: 1. The students must understand the energy transformations known to occur in cells 1. The net ATP generated in the complete oxidation of beta-hydroxybutyrate is: a. 12 ATPs b. 23 ATPs c. 26 ATPs d. 36 ATPs e. 129 ATPs (Harper’s chapter 24) 2. The number of NADPH required in complete synthesis of one (1) mole of palmitic acid a. 7 b. 8 c. 12 d. 14 e. 16 (Harper’s chapter 23) 3. Major source of ATP in aerobic organisms a. direct phosphorylation b. substrate level phosphorylation c. ATP adenylation d. Oxidative phosphorylation 4. The primary pathway for the oxidation of glucose a. Embden Myerhoff pathway b. Sorbitol pathway c. Tricarboxylic acid pathway d. Pentose phosphate pathway (Harper’s ch 14 p137) (Harper’s ch 17 p 173) 5. In the complete oxidation of one (1) mole of palmitic acid to CO2 and H2O, the total number of ATP generated is a. 12 b. 24 c. 36 d. 129 e. 131 (Harper’s Ch 23) 6. Synonymous with Kreb’s cycle a. Pentose phosphate pathway b. Citric acid cyle c. Oxidative phosphorylation d. Embden myerhoff pathway (Harper’s ch 18 p 182f) 7. Anaerobic glycolysis produces how many moles of ATP per mole of glucose? a. 2 b. 6 c. 8 d. 12 e. 24 (Harper’s ch 19 p 190-191) 8. Rate limiting enzyme and the major regulatory enzyme in glycolysis a. triose phosphate isomerase b. glyceride 3-phosphate dehydrogenase c. phosphofructokinase d. aldolase (Harper’s p 191/194) 9. Enzyme that links glycolysis and the citric acid cycle a. Pyruvate dehydrogenase b. Isocitrate dehydrogenase c. Alpha-ketoglutarate dehydrogenase d. Succinate dehydrogenase (Harper’s ch 29 pp 298…) 10. Oxidative phosphorylation is carried out by respiratory assembly located in a. mitochondrial matrix b. inner mitochondrial membrane c. endoplasmic reticulum d. cytosol ( Harper’s pp 126/ 137….) D. Protein and amino acid chemistry/ metabolism OBJECTIVES: 1. The student must be able to describe the chemical structure and properties of proteins and amino acids 2. The student must be able to understand the principles of amino acid and protein metabolism so they can relate and apply such knowledge to the study of human health and diseases 1. Which of the following amino acid functional group pairs is not correct a) arginine:guanidine b) histidine:imidazole c) phenylalanine: hydroxyphenyl d) tryptophan : indole e) cysteine : sulfhydryl (Harper’s p 29) 2.Helical formation or Helix is a characteristic of what protein structure? a. primary b. secondary c. tertiary d. quaternary e. all of the above (Harper’s p 49) 3. Which of the following amino acids serve as the major mode of disposing ammonia from the brain? a. alanine b. glutamine c. threonine d. serine e. valine (Harper’s p 308/317) 4. Among the following amino acids, which one is converted to pyruvate through transamination reaction? a. alanine b. methionine c. threonine d. valine ( Harper’s pp315-316) 5. Which of the following amino acids is convertible to pyruvate by direct deamination? a. alanine b. cysteine c. glycine d. serine e. threonine 6.The amino acid precursor of catecholamines: a. glycine b. proline c. threonine d. tryptophan e. tyrosine ( Harper’s p 354) 7. Among the following amino acids, which one is purely ketogenic? a. isoleucine b. leucine c. phenylalanine d. threonine e. tryptophan ( Harper’s Chapter 4) 8. Urea is the major pathway of nitrogen excretion in humans. It is synthesized in the: a. brain b. intestine c. kidney d. liver e. skeletal muscle ( Harper’s pp315…) 9. Among the intermediates in urea cycle, which one provides the linkage of urea cycle and the citric acid cycle? a. Alpha ketoglutarate b. aspartate c. fumarate d. malate e. oxaloacetate (Harper’s pp319-321) 10. The following amino acid is GLYCOGENIC ONLY a. aspartate b. isoleucine c. leucine d. lysine e. tyrosine ( Harper’s Chapter 4) 11. Disorder of amino acid metabolism characterized by “Maple Syrup urine odor”: a. Alkaptonuria b. Isovaleic Acidemia c. Menke’s Disease d. Phenylketonuria 12. What is the Isoelectric pH of albumin? a. 4.2 b. 4.7 c. 4.9 d. 5.2 e. 5.7 13. The main mode of linkage in primary protein structure is a. hydrogen bonds b. peptide bonds c. salt bonds d. covalent disulfide bonds e. van der waals (Harper’s p 49) 14. Which of the following amino acids contain indole functional group? a. Arginine b. Histidine c. Phenylalanine d. Tryptophan e. Tyrosine (Harper’s p 29) 15. A biochemical technique used to separate molecules based on both size and charge a. gel electrophoresis b. spectrophotometry c. ultracentrifugation d. paper chromatography ( Harper’s P48/53) 16. Which of the following enzymes funnel amino nitrogen from glutamate to urea? a. glutamate transaminase a. alanine transaminase b. amino acid oxidase c. glutamate dehydratase d. glutamate dehydrogenase (Harper’s pp319-321) 17. Amino acid precursor of serotonin a. alanine b. aspartate c. tryptophan d. methionine e. tyrosine 18. The metabolism of the following amino acid leads to the production of small amounts of nicotinic acid in humans a. cysteine b. methionine c. serine d. tryptophan e. valine ( Harper’s chapter 42) 19. A metabolite of the following amino acid is a substrate for branched-chain keto-acid dehydrogenase a. arginine b. lysine c. methionine d. proline e. valine ( Harper’s chapter 4) 20. Which of the following is a non essential amino acid? a. leucine b. tyrosine c. lysine d. methionine e. valine ( Harper’s chapter 4) D. Nucleic acid chemistry/metabolism/ Genetics OBJECTIVES: 1. The student should be able to describe the structural organization of nucleosides, nucleotides and nucleic acids and relate them to their cellular functions 2. The students should discuss and understand the biochemical basis of diseases resulting from impairment in the biosynthetic and catabolic pathways of purine and pyrimidine nucleotide metabolism 1. The most abundant free nucleotide in mammalian cells Adenosine diphosphate Cyclic AMP Adenosine triphosphate Adenosine monophosphate Phosphoadenosine phosphosulfate ( HARPER’S 25th p. 379) 2. A purine analog which is widely used in the treatment of gout a. aspirin b. azathioprine c. allopurinol d. 5-iododeoxyuridine e. 5-flourouracil (HARPER’S CH 35 p-382) 3. Okasaki fragments are a. short non coding DNA segments b. short DNA fragments attached to RNA primers during replication c. produced when histone biosynthesis is inhibited d. mitochondrial DNA fragments complexed with histones (HARPER’S CH 38 p- 424) 4. RNA and DNA diifer from each other , in that: a. in DNA, the nucleotides run 5’ to 3’ direction b. in RNA, the sugar is linked to the base by an N-glycosidic linkage c. In RNA, the sugar is D-ribose d. in DNA, thymine is found instead of uracil ( HARPER’S CH 37 p 406) 5. Detection of purines and pyrimidines can be done because of their strong absorption of UV light at this wavelength a. 260nm b. 650 nm c. 400nm d. 600 nm (HARPER’S p-290) 6. In genetic diseases, the primary defect resides in this organelle a. endoplasmic reticulum b. nucleus c. cytoplasm d. mitochondria ( HARPER’S CH 63 P-813) 7. d. thymine A PURINE BASE a. cytosine b. guanine c. uracil ( HARPER’s ch 37 p 402) 8. Serves as the carrier of genetic information to the site of protein synthesis a. mRNA b. tRNA c. rRNA d. snRNA (HARPER’s ch37 p 407) 9. A synthetic nucleotide analog which exhibits antiviral activity useful in the treatment of herpetic keratitis a. azathioprine b. 5-iododeoxyuridine c. cytarabine d. mercaptopurine ( HARPER’s p 383) 10. Nucleotide derivative that acts as “ secondary messenger” a. ATP b. ADP c. c-AMP d. c-GMP e. GTP ( HARPER’s CH 35 p-380) E. ENZYMES OBJECTIVES: 1. The students must appreciate hoe protein structures of enzymes have been specifically designed to allow the catalytic action of enzymes in metabolic reactions 2. The students must understand the role of enzymes in metabolic regulation and their importance as diagnostic aids and therapeutic tools 1. Two constants are always measured whenever an enzyme is characterized. These are: a. K1 and Km b. Km and Vmax c. Q10 and Vo d. Vmax and Q10 e. Vo and K1 (Harper’s pp 95 ff ) 2. Group of enzymes that catalyze the addition or removal of water, ammonia or carbon dioxide to double bonds: a. hydrolases b. isomerases c. ligases d. lyases e. oxidoreductases 3. Nonfunctional serum enzyme that is diagnostic of obstructive liver diseases. A. acid phosphatase B. alanine aminotransferase C. alkaline phosphatase D. aspartate aminotransferase E. ceruloplasmin 4. Carbonic anhydrase requires which metal ion as cofactor a. iron b. zinc c. magnesium d. copper e. sodium, 5. In the effects of substrate concentration on reaction velocity, when substrate concentration is low a. the reaction velocity is zero order b. the reaction velocity is first-order c. the reaction velocity is second order d. the reaction velocity is mixed order 6. Which of the following is the target enzyme of an anti inflammatory drug, aspirin? a. xanthine oxidase b. transpeptidase c. HMG CoA reductase d. Cyclooxygenase e. Monoamine oxidase 7. Effect of uncompetitive inhibitors to the Maximum velocity (Vmax) and Michaelis constant (Km) a. Vmax - none : Km – increases b. Vmax – decreases : Km – decreases c. Vmax – decreases : Km - none d. Vmax – decreases : Km- increases e. Vmax – increase : Km – none (Harper’s pp 95 ff ) 8. The quantitative value of the Michaelis constant or Km, is a measure of a. the optimum condition present in the cell b. relative affinity between the substrate and enzyme c. the velocity of the biochemical reaction d. the concentration of the enzyme present (Harper’s pp 95 ff ) 9. This enzyme is valuable in the diagnosis of metastatic carcinoma of the prostate gland. a. ceruloplasmin b. alkaline phosphatase c. lactate dehydogenase d. acid phosphatase e. aspartate aminotransferase 10. A group of enzymes that join two molecules along with breakdown of a pyrophosphate (P-P) bond a. ligase b. isomerase c. lyase d. transferase 1. F. HORMONES/ Hormone actions OBJECTIVES: The students must understand the structures, properties and the roles of hormones in the maintenance of normal body metabolism 1. Among the following hormones, which one possess anti-inflammatory effect mediated through the inhibitory effect on arachidonic acid release? a. adrenaline b. glucagon c. glucocorticosteroid d. insulin e. thyroxine 2. Of the following, which is a C-19 steroid? a. cholic acid b. cortisol c. estradiol d. progesterone e. testosterone ( Harper’s 577-578) 3. . Which of the following hormones is aromatic? a. aldosterone b. cortisol c. estradiol d. progesterone e. testosterone ( Harper’s p 577) 4. In the synthesis of estradiol which of the following hormone is its immediate precursor? a. androstenedione b. corticosterone c. pregnenolone d. progesterone e. testosterone ( Harper’s pp599-601) 5. Site of aldosterone secretion in the adrenal cortex: a. zona fasciculata b. zona granulosa c. zona intima d. zona pellucida e. zona reticularis 6. Which of the following is a C-24 steroid? a. chenodeoxycholic acid b. cortisol c. estradiol d. progesterone e. testosterone (Harper’s p 292) 7. Of the following hormones, which one is an essential requirement for triacyglycerol synthesis in the adipose tissue? a. adrenaline b. cortisol c. glucagon d. insulin e. thyroxine (Harper’s p246) 8. In the adipose tissue, which of the following hormones enhances the synthesis of lipoprotein lipase? a. cortisol b. epinephrine c. glucagons d. insulin e. progesterone ( Harper’s p 246) 9. The urinary metabolite used in the diagnosis of Adrenal Pheochromocytoma: a. hydroxyindoleacetic acid (HIAA) b. hydroxytryptamine c. hydroxytryptophan d. normetanephrine e. vanillylmandelic acid (VMA) (Harper’s p 593) 10. . Which of the following is a C-18 steroid? f. chenodeoxycholic acid g. cortisol h. estradiol i. progesterone j. testosterone ( Harper’s p577) E. VITAMINS AND MINERALS OBJECTIVES: 1. The students must understand clearly the nutritional aspects of vitamins and minerals and appreciate their role in the maintenance of normal body functions 2. The students must correlate the clinical disorders that will result from the deficiency and excesses of these vitamins with their metabolic roles in the body. 1. An important anti oxidant because it inhibits the formation of nitrosamines during digestion a. retinol b. ascorbic acid c. tocopherol d. retinoic acid e. cobalamin (Harper’s pp640-641) 2. Deficiency of this may lead to anemia in the prematures due to red blood cell hemolysis a. Vit A b. Vit D c. Vit E d. Vit C e. Vit K (Harper’s pp 647-648) 3. A cofactor of an important enzyme of the pentose phosphate pathway, transketolase a. Thiamine b. Biotin c. Niacin d. Riboflavin e. Pantothenic acid (Harper’s pp 627) 4. Functions as a cofactor to a carboxylase that acts on glutamate residues of clotting factor precursor proteins a. Vitamin A b. Vitamin C c. Vitamiin E d. Vitamin K e. Biotin ( Harper’s PP 649) 5. A polyisoprenoid compound containing a cyclohexenyl ring a. Folic acid b. Pyridoxine c. Ascorbic acid d. Retinol e. Biotin ( Harper’s p 642) 6. The earliest clinical symptom of Vitamin A deficiency a. defective night vision b. xerophtalmia c. presence of Bitots spots d. Keratomalacia e. Xerosis conjunctivae (Harper’s p 643) 7. phosphate metabolism a. Vitamin A b. Vitamin E c. Thiamin d. Folic acid e. Vitamin D This vitamin is important in the regulation of calcium and ( Harper’s p 645) 8. If a patient exhibits low activity of propionyl CoA carboxylase, therapeutic doses of which of the following might be beneficial? a. carnitine b. pantothenic acid c. biotin d. riboflavin e. niacin ( Harper’s p 635) 9. Strict vegetarians are susceptible to this kind of vitamin deficiency a. pantothenic acid b. cobalamin c. folacin d. niacin e. pyridoxine ( Harper’s p 635) 10. . Of the following, which is the most potent form of vitamin D? a. ergosterol b. cholecalciferol c. 7-dehydrocholesterol d. 25-hydroxycholecalciferol e. 1,25-dihydroxycholecalciferol ( Harper’s p 647)
