Each of the following statements is followed by five suggested answers or completions. On the answer sheet, mark the one which is best in each case. 2 POINTS EACH
1. The isoelectric point of alanine is 6.0. If alanine is dissolved in a buffer of pH 8.0 it will
A. have a net positive charge
B. be electrically neutral
C. have a net negative charge
D. have no negatively charged groups
2. In anaerobic glycolysis, pyruvate does not accumulate because
A. lactate dehydrogenase consists of five isoenzymes
B. pyruvate is converted to acetylCoA by pyruvate dehydrogenase
C. the ratio of NADH/NAD is low in the cytoplasm
D. it is reduced to lactate by cytosolic lactate dehydrogenase
E. it is oxidized by the citric acid cycle
3. All of the following are true concerning fibrin EXCEPT:
A. it is formed during primary hemostasis
B. it is formed from fibrinogen by specific cleavage by thrombin.
C. it does not have intrinsic protease activity
D. it becomes covalently crosslinked to stabilize a clot
E. it is normally degraded by plasmin
4. The major lipids found in membranes are
A. triacylglycerols and cholesterol
B. cholesterol and sphingomyelin
C. phospholipids, glycolipids, and cholesterol
D. phospholipids and free fatty acids
E. cholesterol, inositol, and glycolipids
5. In proteins, the side chain of serine can be involved in all of the following EXCEPT:
A. phosphorylation
B. hydrogen bonding
C. covalent carbohydrate attachment
D. ionic interactions
E. enzymatic catalysis
6. All of the following enzymes carry out substrate level phosphorylations EXCEPT
A. ATP synthase
B. phosphoglycerate kinase
C. pyruvate kinase
D. succinyl CoA synthetase
7. During glycolysis NADH is produced in the cytosol. Under aerobic conditions, what is the primary fate of this NADH?
A. It accumulates in the cytosol
B. It diffuses into the mitochondria
C. It transfers its reducing equivalents directly to NADP+
D. The reducing equivalents are transferred by a shuttle system to the mitochondrial electron transport system
E. It is used to reduce glucose to sorbitol
8. The major pathway by which mature red cells generate ATP is:
A. aerobic metabolism.
B. anaerobic glycolysis.
C. hexose monophosphate shunt activity.
D. generation of 2,3-diphosphoglycerate.
E. fatty acid oxidation.
9. All of the following would be likely in an untreated case of Type I (insulin-dependent) diabetes EXCEPT
A. increased fatty acid oxidation
B. lowered levels of glucose and glucose 6-phosphate in muscle cells
C. high levels of glycogen synthesis in liver
D. high blood fatty acid levels
E. high blood glucose levels
10. The absorption of glucose from the intestinal lumen into mucosal cells:
A. does not require a carrier protein.
B. requires bile salts
C. occurs down a glucose concentration gradient.
D. depends on the sodium ion gradient.
E. occurs through an insulin-responsive glucose transporter
11. Which of the following enzymes are unique to gluconeogenesis (as opposed to glycolysis)?
1. glucose 6-phosphatase
2. pyruvate kinase
3. PEP carboxykinase
4. aldolase
A. 1
B. 1 and 3
C. 2 and 4
D. 1, 2, and 3
E. all of them
12. In biological systems, which compound mediates transfer reactions involving the "one-carbon" pool in multiple oxidation states?
A. S-adenosyl methionine.
B. pyridoxal phosphate.
C. tetrahydrofolic acid.
D. vitamin K.
E. biotin.
13. In the Cori cycle, the product made by liver cells and returned to muscle is
A. acetyl CoA
B. glucose
C. palmitic acid
D. alanine
E. lactate
14. Which of the following is a pancreatic zymogen that is activated directly by enteropeptidase (enterokinase)?
A. trypsinogen
B. chymotrypsinogen
C. carboxypeptidase
D. proelastase
E. prothrombin
15. Which of the following enzymes are involved in the EXCISION-REPAIR of UV-induced pyrimidine dimers?
1. an endonuclease
2. DNA ligase
3. DNA polymerase I
4. photoreactivating enzyme (DNA photolyase)
A. 1
B. 1 and 3
C. 2 and 4
D. 1, 2, and 3
E. all of them
16. Concerning the biosynthesis of urea by humans, each of the following statements is correct EXCEPT
A. the first nitrogen atom entering the urea cycle does so in the form of carbamoyl phosphate
B. the second nitrogen atom entering the urea cycle is supplied by the amino group of aspartate
C. the process occurs primarily in the liver
D. the immediate precursor of urea is ornithine from which urea is cleaved by ornithase
E. some of the reactions of the urea cycle occur in the mitochondrial matrix and some in the cytoplasm
17. Fatty acids from adipose tissue are transported to sites of utilization in the form of:
A. triglycerides bound to serum albumin.
B. very low density lipoproteins.
C. high density lipoproteins.
D. chylomicrons.
E. free fatty acids bound to serum albumin.
18. An intermediate common to the biosynthesis of cholesterol and the biosynthesis of ketone bodies is
A. methylmalonyl-CoA
B. succinyl-CoA
C. cholyl-CoA
D. 5-phosphomevalonic acid
E. HMG-CoA
19. Which of the groups below contains two compounds that are parts of coenzymes involved in the beta-oxidation of fatty acids?
A. Vitamin D and pantothenic acid
B. Biotin and folic acid
C. Niacin and riboflavin
D. Pyridoxine and thiamine
E. Choline and carnitine
20. All of the following are true for both DNA polymerase and RNA polymerase EXCEPT which one?
A. both require a template
B. both reactions produce pyrophosphate as a product
C. both add 5' nucleotides to 3' hydroxyl groups
D. both utilize nucleotide triphosphates as substrates
E. both require a primer
21. What will be the effect of a single base pair deletion in the middle of a DNA sequence coding for a certain protein?
A. a protein with a single amino acid substitution in its center
B. the gene will not be transcribed and no protein will be produced
C. the amino half of the protein will have a normal sequence
D. the carboxyl half of the protein will have a normal sequence
E. DNA polymerase will repair the damage
22. Which of the following is not one of the important criteria that is considered in determining if a genetic disease is a good candidate for gene therapy?
A. the gene defect must be known and the normal gene must be cloned and characterized
B. the disease should be life threatening with no adequate therapy
C. optimally the genetic defect should be due to a dominant mutation
D. the target tissue should be easily accessible
E. it should be encoded by a single copy gene
23. In the regulation of an overall metabolic sequence, which of the following reactions is most likely to be modulated by allosteric effectors?
A. All steps have equal probability to be regulated
B. The last reaction of the sequence.
C. The initial committed step of the sequence.
D. The fastest reaction of the sequence.
E. A reaction with an overall equilibrium constant of one
24. The genetic code is degenerate means:
A. one codon codes for more than one amino acid
B. there is more than one codon for some amino acids
C. both DNA strands are used as templates for mRNA synthesis
D. the code varies from species to species
E. there is more than one aminoacyl tRNA synthetase for each amino acid
25. Allosteric control of enzyme action requires
A. a cofactor derived from a vitamin.
B. a metal ion.
C. the conversion of one form of the enzyme to another by the action of proteolytic enzymes.
D. a conformational change in an enzyme that changes its catalytic activity.
E. an effector that is the product of the enzymatic reaction and which competes with the normal substrate for the active site of the enzyme.
26. An enzyme present in the liver but NOT in muscle is
A. hexokinase.
B. glucose 6-phosphatase.
C. lactate dehydrogenase.
D. pyruvate dehydrogenase.
E. glycogen phosphorylase.
27. All of the following compounds are carbon sources for the net synthesis of glucose in liver EXCEPT
A. lactate.
B. beta-hydroxybutyrate.
C. alanine.
D. aspartate.
E. glycerol.
28. The absence of which factor is responsible for classical hemophilia A?
A. Factor II
B. Factor V
C. Factor VII
D. Factor VIII
E. Factor XIII
29. Which of the following are positive allosteric effectors of phosphofructokinase-1?
1. ATP
2. fructose 2,6-bisphosphate
3. citrate
4. AMP
A. 1
B. 1 and 3
C. 2 and 4
D. 1, 2, and 3
E. all of them
30. Which of the following statements about hemoglobin S is correct?
A. It is the normal hemoglobin found in most adults
B. It is a form of hemoglobin modified by the addition of a cysteine at the C-terminus
C. It is a mutant form of hemoglobin in which a specific glutamic acid in each chain has been replaced by a valine and has a tendency to form insoluble aggregates
D. It is a mutant form of hemoglobin that makes one more susceptible to infection by the malarial parasite
E. It is a mutant form of hemoglobin that aggregates in the presence of high oxygen concentrations
31. The regions of variable amino acid composition of immunoglobulins occur in
A. heavy chains only
B. light chains only
C. both light and heavy chains
D. IgG but not other immunoglobulins
E. IgM but not other immunoblobulins
32. A patient has chest pains that began 6 hours earlier. Which of the following would be most useful to indicate the presence of a myocardial infarction at this time?
A. elevated MB fraction of creatine kinase in serum
B. elevated MM fraction of creatine kinase in serum
C. elevated LDH fraction 5 in serum
D. elevated LDH fraction 1 in serum
E. elevated BUN (blood urea nitrogen)
33. Pyruvate can be converted in one step, catalyzed by a single enzyme or enzyme complex, to each of the following EXCEPT
A. malonyl-CoA
B. oxaloacetate
C. lactate
D. acetylCoA
E. alanine
34. Xeroderma pigmentosum results from a deficiency in
A. collagen synthesis
B. DNA replication
C. DNA repair
D. bilirubin conjugation
E. a tumor suppressor
35. The rate of an enzyme catalyzed reaction
1. can be determined by measuring the increase in product concentration with respect to time.
2. is usually dependent on temperature and pH.
3. at saturating substrate concentrations, becomes zero-order with respect to substrate.
4. is independent of the enzyme concentration.
A. 1
B. 1 and 3
C. 2 and 4
D. 1, 2, and 3
E. all of them
36. During prolonged starvation, the brain oxidizes significant amounts of
1. glucose.
2. fatty acyl carnitine.
3. acetoacetate.
4. free fatty acids.
A. 1
B. 1 and 3
C. 2 and 4
D. 1, 2, and 3
E. all of them
37. The primary failure in collagen biosynthesis which results in scurvy is
A. improper translation of the pro-alpha-chains
B. incorrect formation of disulfide bonds
C. insufficient interstrand crosslinking
D. insufficient hydroxylation of proline and lysine
E. improper cleavage of procollagen
38. A drug that lowers blood urate levels by inhibiting the conversion of hypoxanthine to xanthine is
A. cholestyramine
B. allopurinol
C. methotrexate
D. 5-fluorouracil
E. puromycin
39. Which of the following proteins would not be expected to be synthesized in a form that contains a signal peptide that is recognized by SRP?
A. insulin
B. lysosomal beta-hexosaminidase
C. beta-adrenergic receptor
D. trypsinogen
E. hexokinase
40. Which of the following amino acids is most likely to be found on the surface of a globular protein in an aqueous environment?
A. phenyalanine
B. methionine
C. leucine
D. valine
E. aspartate
41. Adenylate cyclase
A. is activated by direct contact with beta-adrenergic receptors
B. is activated by direct contact with the GaS subunit
C. can synthesize cyclic GMP as well as cyclic AMP
D. is inactivated by a phosphodiesterase
E. is a second messenger
42. For a competitive enzyme inhibitor
A. Vmax is decreased by a factor of 1 + I/KI
B. the Vmax is unaffected
C. the effects are irreversible
D. the Km is unaffected
E. the Km is decreased by a factor of 1 + I/KI
43. All of the following are a part of our current concept of biological membranes EXCEPT
A. a fluid lipid bilayer
B. proteins can move in the plane of the membrane
C. proteins are symmetrically distributed on both sides of the membrane
D. proteins are inserted into and across the lipid bilayer
E. lipids are asymmetrically distributed on both sides of the membrane
44. A major difference between chylomicrons and VLDL particles is that
A. The major lipid component of chylomicrons is triglycerides while the major lipid component of VLDL is cholesterol esters
B. Lipoprotein lipase removes fatty acids and glycerol from chylomicrons while hormone sensitive lipase removes them from VLDL
C. Chylomicrons carry triglycerides assembled in the intestinal mucosal cells from dietary sources while VLDL carries triglycerides primarily synthesized by the liver
D. Chylomicrons carry triglycerides away from the liver while VLDL primarily returns them to the liver from other tissues
E. Only chylomicrons have apolipoprotein C2
45. The major site quantitatively of cholesterol biosynthesis in the human is
A. intestinal epithelia
B. gall bladder
C. pancreas
D. adrenal gland
E. liver
46. Sulfa drugs such as sulfanilamide are effective against certain pathogenic bacteria because
A. they block the synthesis of dihydrobiopterin
B. they block the synthesis of niacin
C. they block the synthesis of folate
D. they block the synthesis of pyridoxal
E. they block the synthesis of thiamine
47. The absorption of which of the following vitamins would most likely be lowered by treatment for high cholesterol levels with bile acid sequestrants such as cholestyramine?
A. vitamin C
B. vitamin E
C. biotin
D. pantothenic acid
E. thiamine
48. Which of the following is true for hemoglobin but not for myoglobin
A. it contains a heme group
B. it is highly alpha-helical
C. it binds oxygen
D. it exhibits positive cooperativity
E. the iron atom is in the +2 valence
49. The function of the enzyme acetylcholine esterase is to
A. concentrate acetylcholine in synaptic vesicles by exchanging it for protons
B. to signal the release of acetylcholine into the synaptic cleft
C. to clear acetylcholine after it has been secreted into the synaptic cleft
D. to synthesize acetylcholine from acetylCoA and choline
E. to bind to receptors on the postsynaptic membrane
50. A collection of recombinant DNA clones representing all of the various mRNA molecules from a certain cell type is a:
A. probe
B. genomic library
C. cDNA library
D. vector
E. restriction digest
51. A restriction enzyme would not be required for which of the following recombinant DNA techniques:
A. RFLP analysis
B. Southern blot analysis of genomic DNA
C. Preparation of a genomic library
D. Polymerase chain reaction (PCR)
52. Enzymes do all of the following EXCEPT:
A. increase the rate of a reaction
B. lower the activation energy of a reaction
C. alter the equilibrium constant of a reaction
D. act specifically on one substrate or a group of related substrates
53. Which of the following steps in collagen biosynthesis takes place outside of the cell?
A. intermolecular crosslinking
B. hydroxylation of lysine
C. hydroxylation of proline
D. triple helix formation
E. glycosylation
54. The receptor protein for light in retinal cells is
A. cis retinal
B. all trans retinal
C. cGMP
D. rhodopsin
E. transducin
55. The antitumor reagent methotrexate functions by
A. directly inhibiting the enzyme dihydrofolate reductase
B. inhibiting synthesis of folate
C. directly inhibiting the enzyme thymidylate synthase
D. blocking absorption of vitamin B12
E. inhibiting oxidation of folic acid
56. A direct intracellular target of nitric oxide is
A. adenylate cyclase
B. guanylate cyclase
C. IP3
D. protein kinase C
E. calmodulin
57. In malignant hyperthermia, administration of certain anesthetics to sensitive people results in the rapid development of a tremendous fever, rapid breathing and energy insufficiency. The most likely cause of malignant hyperthermia is
A. blockage of a glycolytic enzyme.
B. uncoupling of oxidative phosphorylation.
C. inhibitor of fatty acid oxidation.
D. stimulation of epinephrine release.
E. inhibition of mitochondrial electron transport
58. Pyridoxal phosphate acts as a coenzyme in all of the following reactions EXCEPT
A. aminotransferase reactions (transaminases).
B. biosynthesis of cys from met and ser.
C. decarboxylation of glu to form GABA.
D. decarboxylation of pyruvate to form acetyl CoA.
E. biosynthesis of heme from succ CoA and glycine.
59. An infant presents with symptoms of Maple Syrup Urine disease. If the defect involved a mutation resulting in an increased Km of the defective enzyme, which of the following vitamins in megadoses could possibly alleviate the symptoms?
A. vitamin B12
B. folic acid
C. biotin
D. thiamine
E. vitamin B6 (pyridoxamine)
60. Enzymes which are classified as serine hydrolases include all of the following EXCEPT:
A. trypsin
B. chymotrypsin
C. acetylcholine esterase
D. thrombin
E. lysozyme
61. What is the most plausible explanation for impaired pentose phosphate pathway metabolism in alcoholics:
A. low blood glucose
B. high blood glucose
C. low transketolase activity due to a thiamine deficiency
D. low glucose-6-P dehydrogenase activity due to a thiamine deficiency
E. impaired electron transport due to high levels of alcohol
62. The major regulatory step in glycolysis can be bypassed in the catabolism of which of the following carboydrates:
A. glycogen
B. glucose
C. galactose
D. fructose
E. maltose
63. Removal of the chief metabolite of cholesterol from the body is used in the treatment of hypercholesterolemia. Therapy is directed toward the elimination of
A. ketone bodies
B. cortisol
C. progesterone
D. bile salts
E. acetyl CoA
64. The final product of glycolysis in human cells under anaerobic conditions or in cells lacking mitochondria is
A. carbon dioxide
B. ethanol
C. lactate
D. phosphoenol pyruvate
E. pyruvate
65. Myoglobin exhibits all of the following types of structure EXCEPT:
A. primary
B. secondary
C. tertiary
D. quaternary
66. Which of the following is most important in establishing the secondary structure of a protein?
A. disulfide bonds
B. ionic bonds
C. hydrogen bond
D. hydrophobic forces
E. van der Waals forces
67. A deficiency of pyruvate carboxylase leads to a decrease in cellular
A. acetyl CoA
B. Kreb's cycle intermediates
C. lactate
D. biotin
E. alanine
68. A sample of the enzyme defective in Maple Syrup Urine disease was isolated from the infant in question #59, and its kinetic dependence on the appropriate cofactor were determined by means of a Lineweaver Burk (double reciprocal) plot. Which of the following lines represents the data for the patient?
69. Failure to digest dietary lipids leads to steatorrhea. All of the following substances are required for digestion of dietary lipid EXCEPT
A. bile pigments
B. bile salt
C. colipase
D. pancreatic lipase
E. pancreatic phospholipase
70. The circulating form of hemoglobin that is used to assess chronic blood glucose concentrations in diabetes mellitus is
A. hemoglobin A
B. hemoglobin A1c
C. hemoglobin F
D. hemoglobin H
E. hemoglobin S
71. A deficiency of which one of the following enzymes leads to diarrhea and failure to thrive in newborns owing to inadequate cleavage of trypsinogen to trypsin in the intestinal lumen?
A. carboxypeptidase A
B. enterokinase (enteropeptidase)
C. furin
D. leucine aminopeptidase
E. pepsin
72. Which one of the following proteins possesses protein-tyrosine kinase activity?
A. AMP-dependent protein kinase
B. fructose-6-phosphate 2-kinase/fructose-2,6-biphosphatase
C. glucagon receptor
D. insulin receptor
E. pyruvate dehydrogenase kinase
73. Phenylketonuria, alkaptonuria, and albinism are caused by deficiencies in enzymes involved in the metabolism of
A. tryptophan
B. phenylalanine
C. histidine
D. valine
E. lysine
74. Mutation of which one of the following tumor suppressor genes can lead to multiple eye tumors in children?
A. Bcl-2
B. NF1
C. p53
D. RB1
E. WT1
75. Which one of the following is a true statement regarding fluorouracil?
A. It is an alkylating agent.
B. It inhibits human topoisomerase II.
C. It inhibits dihydrofolate reductase.
D. It is a hormone antagonist.
E. It is converted to an inhibitor of thymidylate synthase.
76. Which one of the following binds calcium and then undergoes a conformational change that triggers striated muscle contraction?
A. calsequestrin
B. tropomyosin
C. troponin I
D. troponin C
E. troponin T
77. Several types of osteogenesis imperfecta (brittle bone disease) are due to point mutations involving which one of the following amino acids?
A. alanine
B. glycine
C. hydroxylysine
D. hydroxyproline
E. proline
78. Which of the following may be involved in the intracellular transmission of hormonal action?
A. cAMP
B. inositol triphosphate
C. tyrosine kinase
D. protein kinase C
E. all of the above
79. Which one of the following enzymes catalyzes the elimination of nicks or discontinuities in DNA that occur during DNA repair or in the linking together of Okazaki fragments?
A. AP exonuclease
B. DNA gyrase
C. DNA ligase
D. topoisomerase I
E. topoisomerase II
80. Each one of the following statements describes both human and bacterial DNA EXCEPT
A. The DNA occurs physiologically as nucleosome complexes.
B. The DNA contains major and minor grooves.
C. The DNA consists of an antiparallel duplex.
D. The DNA conains equal molar fractions of adenine and thymine.
E. The DNA contains equal molar fractions of guanine and cytosine.
81. Aspirin is an irreversible inhibitor of
A. cyclooxygenase
B. lipoxygenase
C. phospholipase A1
D. phospholipase A2
E. phospholipase C
82. Reversing the effects of the glucagon cascade in the liver involves all of the following processes EXCEPT
A. cessation of adenylyl cyclase stimulation
B. conversion of cyclic AMP to 5'-AMP
C. reformation of the inactive R2C2 form of protein kinase A
D. dephosphorylation of phosphatase-1 inhibitor, phosphorylase a, phosphorylase kinase, glycogen synthase, fructose-6-phosphate-2-kinase/phosphatase, and pyruvate kinase
E. increased dephosphorylation of fructose 1,6-bisphosphate to form fructose 6-phosphate
83. All of the following DNA sequences play an important role in mediating human gene expression EXCEPT
A. TATA box
B. CAAT box
C. GC box
D. enhancers
E. lac Operon
84. GTP hydrolysis is required for each of the following activities in protein synthesis EXCEPT
A. chain initiation
B. implanting aminoacyl-tRNA into the A site
C. the peptidyltransferase reaction
D. translocation
E. chain termination and dissociation of the ribosomal subunits
85. Gelatin, a foodstuff that is derived from collagen, lacks tryptophan and cysteine. A diet that consists only of gelatin leads to a negative nitrogen balance nitrogen excretion exceeds nitrogen intake) and decreased protein synthesis. The primary mechanism responsible for decreased protein synthesis in a diet lacking tryptophan is
A. decreased ATP production
B. failure to synthesize any aminoacyl-tRNA
C. failure of mRNAs containing codons corresponding to tryptophan to bind to ribosomes
D. failure to form an initiation complex
E. failure to elongate polypeptides directed by mRNAs containing codons corresponding to tryptophan
86. Which one of the following is a true statement regarding transducin?
A. It is a seven-transmembrane-segment protein
B. It consists of alpha-, beta-, and gamma-subunits that resemble those of Gs and Gi
C. It catalyzes the hydrolysis of cyclic GMP
D. It contains 11-cis retinal
E. It directly opens a cation channel
87. Cholera toxin catalyzes the ADP-ribosylation of which one of the following proteins?
A. Ovaltine
B. Gi
C. Gi
D. Gs
E. EF-2
88. All of the following are considered essential amino acids in the adult EXCEPT:
A. leucine
B. lysine
C. methionine
D. valine
E. asparagine
89. All of the following statements show biological information transfer occurring in a correct direction EXCEPT
A. DNA --> RNA
B. RNA --> DNA
C. RNA --> protein
D. DNA --> DNA
E. Protein --> RNA
90. Which of the following pathways is most important in the mature red blood cell?
A. pentose phosphate pathway
B. oxidation of fatty acids
C. citric acid cycle
D. ketone body synthesis
E. fatty acid synthesis
91. Which of the following would be least likely to occur in advanced cases of marasmus.
A. ketone bodies used by the brain
B. liver glycogen depleted
C. high insulin:glucagon ratio in blood
D. liver gluconeogenesis
E. oxidation in the liver
92. Which of the following descriptions of glycogen in NOT true?
A. glycogen is composed of glucose linked by alpha 1-4 and alpha 1-6 linkages
B. glycogen is very hydrophilic
C. glycogen is stored in granules in the cytosol
D. the reducing end of glycogen is attached to glycogennin
E. glycogen is degraded starting at the reducing end.
93. Which of the following enzymes is the important regulatory point in the beta-oxidation of fatty acids?
A. fatty acid synthase
B. carnitine acyl transferase I
C. HMG CoA reductase
D. fatty acyl CoA synthetase
E. acyl CoA dehydrogenase
94. Each of the following statements about heme and iron metabolism is correct EXCEPT:
A. iron is stored in the liver as ferritin
B. iron is transported in the plasma bound to transferrin
C. iron as Fe2+ is inserted into protoporphryin IX in the last step of heme synthesis
D. the iron produced by heme degradation is primarily excreted in the feces
E. uptake of iron by cells requires a specific receptor which is recycled to the plasma membrane.
95. Which of the following amino acids is involved in the formation of disulfide bridges?
A. methionine
B. hydroxyproline
C. tryptophan
D. tyrosine
E. cysteine
96. All of the following enzymes are activated by protein kinase A EXCEPT:
A. hormone sensitive lipase (adipose)
B. phosphorylase
C. fructose-2,6-bisphosphatase
D. phosphorylase kinase
E. glycogen synthetase
97. Which of the following is a result of epinephrine signalling to the muscle.
A. dephosphorylation of glycogen synthase
B. dephosphorylation of glycogen phosphorylase
C. activation of cAMP phosphodiesterase
D. phosphorylation of phosphorylase kinase
E. synthesis of new glycogen
THIS CASE REFERS TO QUESTIONS 98-100:
A 29-year-old woman and her 32-year-old husband come to the obstetrics clinic for information and counseling concerning her pregnancy. They had previously had three children. Child I (A 7-year-old girl) and child II (a 4year-old boy) are alive and healthy, and child III (a girl) died of cystic fibrosis at the age of 18 months, 1 year ago.
An ultrasound examination during week 9 showed a dichorionic twin gestation with two placentas. The couple requested prenatal diagnosis. The crown-rump length of both fetuses were 27 mm, corresponding to 9.5 weeks.
Chorionic villus sampling was used to obtain approximately 25 mg of tissue from each placenta. After DNA extraction, polymerase chain reactions were performed. The primers, which were designed to bracket the 508 mutation, led to the production of an 87-base-pair product from a normal CFTR gene and an 84-base-pair product from a 508 mutant gene. The products were subjected to polyacrylamide gel electrophoresis and localized by ethidium bromide staining. The results for the PCR analysis of DNA from the parents, their children, the two fetuses, an unaffected person and DNA containing a 508 mutation established by DNA sequence analysis are illustrated below. MOM DAD CI CII CIII FI FII NORM 508 87 ___ ___ ___ ___ ___ ___ 84 ___ ___ ___ ___ ___ ___ ___
98. Which one of the following is NOT a true statement regarding these results?
A. Child I will be affected with cystic fibrosis
B. Child II is heterozygous for the 508 mutation
C. the father is heterozygous for the 508 mutation
D. the mother is heterozygous for the 508 mutation
E. Child III is homozygous for the 508 mutation
99. Cystic fibrosis is what class of genetic disease?
A. autosomal dominant
B. autosomal recessive
C. X-linked dominant
D. X-linked recessive
100. Which of the fetuses will be affected, according to the results from the polymerase chain reaction methodology?
A. both fetus I and II will be affected
B. fetus I, but not fetus II, will be affected
C. neither fetus I nor II will be affected
D. fetus II, but not fetus I, will be affected
101. Respiratory Distress Syndrome in premature newborns is caused by deficiency in the lungs of:
A. sphingomyelin
B. gangliosides
C. triacylglycerols
D. phosphatidylcholine
E. prostaglandins
102. A person with an LDL-receptor deficiency was treated with lovastatin. As a consequence of the action of this drug, the person should have:
A. fewer LDL receptors in cell membranes
B. increased de novo cholesterol synthesis
C. increased ACAT activity
D. lower blood cholesterol levels
E. higher blood triacylglycerol levels
103. Mutations involving this gene lead to impaired ability to produce chylomicrons, VLDL, and LDL, thereby leading to fat malabsorption, diarrhea, retinitis pigmentosa, cerebellar ataxia, and acanthocytosis.
A. Apoprotein A-1 gene
B. Apoprotein B-100/B-48 gene
C. Apoprotein C-II gene
D. Apoprotein E gene
E. LDL receptor gene
104. All of the following are consequences of alcohol consumption EXCEPT:
A. increased cytosolic NADH levels
B. increased mitochondrial NADH levels
C. increased gluconeogenesis from lactate
D. fatty liver if the consumption is chronic
E. increased activity of the malate-aspartate and alpha-glycerol phosphate "shuttles"
105. An infant is found to have a glucose 6-phosphatase deficiency. Manifestations of this deficiency would include all of the following EXCEPT:
A. an enlarged liver due to glycogen deposits
B. an inability to maintain blood glucose levels by gluconeogenesis
C. an inability to utilize galactose or fructose to maintain blood glucose
D. an enlarged muscle mass due to glycogen deposits
E. an inability to maintain blood glucose levels by glycogenolysis
106. A patient's blood contains 20 mM HC03- and 2 mM total CO2 (C02+ H2C03. The pH of the blood (pKa = 6.1) is:
A. 6.1
B. 7.1
C. 5.1
D. 7.4
E. none of the above
107. A serine protease that has been shown to be involved in the molecular pathway for activating apoptosis is
A. Bcl-2
B. FIRE
C. ICE
D. WIND
E. Bax
108. Patients with Lesch-Nyhan syndrome have a tendency towards periodic aggressive behavior, including self-mutilation (e.g. biting through lip, etc.), besides having problems with gout. Lesch-Nyhan syndrome is due to a mutation in:
A. xanthine oxidase
B. de novo biosynthesis of purines
C. de novo biosynthesis of pyrimidines
D. salvage pathway for purines
E. salvage pathway for pyrimidines
109. A deficiency in which of the following would lead to a decreased ability to handle oxidative stress and cause premature lysis of the erythrocyte under oxidative conditions?
A. defective synthetic pathway for glutathione
B. defective glucose-6-phosphate dehydrogenase
C. defective glutathione reductase enzyme
D. defective glutathione peroxidase
E. all of the above
110. Diabetes mellitus could be caused by:
1. Insufficient secretion of insulin
2. antibodies to pancreatic beta-cells (autoimmune disease)
3. glucokinase mutation
4. ineffective insulin receptors
A. 1,2, and 3
B. 1 and 3
C. 2 and 4
D. 4 only
E. all 4 are correct
111. A 25 year old male insulin-dependent diabetic presents in the emergency room of the hospital after not taking his shots faithfully. Which of the following symptoms would you NOT expect to find?
A. rapid, shallow breathing
B. blood pH = 7.1
C. elevated blood levels of acetoacetate and beta-hydroxybutyrate
D. odor of acetone on his breath
E. severely decreased levels of blood glucose
(112-116) For each description of a biochemical process, select the most appropriate cellular component.
A. cytosol
B. lysosome
C. mitochondrion
D. nucleus
E. peroxisome
F. plasma membrane
G. rough endoplasmic reticulum and Golgi
H. smooth endoplasmic reticulum
112. __________ site of protein glycosylation reactions
113. __________ the therapeutic effect of AZT used in the treatment of AIDS occurs at this site
114. __________ location of alpha-ketoglutarate dehydrogenase
115. __________ final destination of proteins tagged with mannose-6-phosphate
116. __________ site of de novo fatty acid synthesis ------------------------------------------------------------ The following list pertains to questions 117-121
A. Wet beriberi with heart failure
B. Bleeding disorders
C. Kwashiorkor
D. Marasmus
E. Night blindness
F. Pellagra
G. Pernicious anemia
H. Rickets
I. Scurvy
For each of the characteristics listed below, select the most appropriate disease from the list above (A-I).
117. ____________ Deficient intrinsic factor production
118. ____________ Inadequate protein and caloric intake in children
119. ____________ Deficient intake of -carotene
120. ____________ Inadequate thiamine due to chronic alcoholism
121. ____________ Deficient intake of niacin
1-10: C,D,A,C,D,A,D,B,C,D 11-20: B,C,B,A,A (in man) or E (in bacteria), D,E,E,C,E 21-30: C,C,C,B,D,B,B,D,C,C 31-40: C,A,A,C,D,B,D,B,E,E 41-50: B,B,C,C,E,C,B,D,C,C 51-60: D,C,A,D,E,B,B,D,D,E 61-70: C,D,D,C,D,C,B,B,A,B 71-80: B,D,B,D,E,D,B,E,C,A 81-90: A,E,E,C,E,B,D,E,E,A 91-100: C,E,B,D,E,E,D,A,B,D 101-110 D,D,B,C,D,B,C,D,E,E 111-121 E,G,D,C,B,A,G,D,E,A,F ANSWERS