PACOP VIOLET (Biochemistry)

1. What biomolecules are considered the most abundant and functionally diverse in the living system? A. Proteins B. Carbohydrates C. Nucleic acid D. Fatty acid E. Terpenoids

A. Proteins

2. Which of the following statements is correct about protein structure? I. The primary structure of a protein involves alpha-helices, beta-sheets and other types of folding patterns that occur due to a regular repeating pattern of hydrogen bond formation. II. The secondary structure consists of the amino acid sequence along the chain. III. The tertiary structure involves electrostatic and hydrophobic interactions, van der Waals interaction, and hydrogen and disulfide bonds. IV. Quaternary structure refers to the interaction of one or more subunits to form a functional protein, using the same forces that stabilize the tertiary structure. A. I only B. I and II C. II and III D. I and IV E. III and IV

E. III and IV

3. Accumulated misfolded proteins occur in a variety of diseases. Which of the following proteins is misfolded in patients with Alzheimer's disease? A. Prion protein B. Alpha-synuclein C. Glutamine stretches D. Beta-amyloid E. None of these

D. Beta-amyloid

4. Hemoglobinopathies result from mutations that produce alterations in the structure of hemoglobin. One common mutation result is sickle cell anemia, in which a mutated form of hemoglobin distorts the RBC into a crescent shape at low oxygen levels. Sickle cell anemia happens when: A. Valine is being substituted by glutamine at codon number 6 B. Glutamic acid is being substituted by valine at position number 6 C. Glutamine is intercalated by histidine at codon number 6 D. Gene transcription is disrupted E. None of these

B. Glutamic acid is being substituted by valine at position number 6

5. Acid-base disturbances occur under a variety of conditions. Which of the following is the result of hyperventilation due to retention of carbon dioxide in the lungs? A. Respiratory acidosis B. Respiratory alkalosis C. Metabolic acidosis D. Metabolic alkalosis E. Lactic acidosis

A. Respiratory acidosis

6. In amino acids, the pH at which the number of positive charges equals the number of negative charges is termed as: A. Chirality B. Amphoteric property C. Optical activity D. Isoelectric point E. Zwitterions

D. Isoelectric point

7. Molecules that contain an equal number of ionizable groups of opposite charge and that therefore bear no net charge are termed as: A. Chirality B. Amphoteric property C. Optical activity D. Isoelectric point E. Zwitterions

E. Zwitterions

8. Problems associated with connective tissues and structural protein are present in a number of diseases. In scurvy, hydroxylation of proline residues is decreased and an unstable form of collagen is produced. Bones, teeth, blood vessels and other structures rich in collagen develop abnormally. Bleeding gums and poor wound healing are often observed. Which of the following vitamin deficiencies is associated to scurvy? A. Vitamin C B. Vitamin E C. Vitamin A D. Vitamin D E. Vitamin K

A. Vitamin C

9. Which of the following is true about insulin functions? I. Insulin is released from the pancreas when blood glucose levels are elevated II. Insulin promotes the transport of glucose into muscle and fat cells III. Insulin promotes the storage of energy IV. Insulin increases glycogen catabolism in the liver and muscles A. I and II B. I, II and III C. I, II and IV D. I only E. I, II, III, and IV

B. I, II and III

10. The enzyme kinetics can be described by what equation? A. Noyes-Whitney Equation B. Henderson-Hasselbalch Equation C. Arrhenius Equation D. Van Slyke Equation E. Michaelis-Menten Equation

E. Michaelis-Menten Equation

11. Evaluate the given statements. (1) Competitive inhibitors compete with the substrate for binding at the allosteric site of the enzyme. (2) Noncompetitive inhibitors bind to the enzyme or the enzyme-substrate complex at the active site. A. Only I is correct B. Only II is correct C. I and II are correct D. I and II are incorrect

D. I and II are incorrect

12. In phenylketonuria, the enzyme phenylalanine hydroxylase is deficient. Which of the following statements is not true about the condition? A. Phenylketonuria happens as a result of accumulated phenylalanine in the body B. Tyrosine becomes an essential amino acid among phenylketonuric patients C. Aspartame is recommended for phenylketonuric patients D. Phenylalanine non-metabolism leads to mental retardation E. None of these

C. Aspartame is recommended for phenylketonuric patients

13. Which of the following is not a basic amino acid? A. Histidine B. Leucine C. Lysine D. Arginine E. None of these

B. Leucine

14. What are the amide linkages between the alpha-carbonyl group of one amino acid and alpha-amino group of another? A. Peptide bonds B. Disulfide bonds C. Hydrogen bonds D. Hydrophobic bonds E. Ionic bonds

A. Peptide bonds

15. Edman's reagent is used to label the amino-terminal residue under mildly alkaline conditions. What is the component of this reagent? A. Monosodium glutamate B. Alpha-naphthol C. Picric acid D. Phenylisothiocyanate E. None of these

D. Phenylisothiocyanate

16. Several different polypeptide helices are found in nature, but the alpha-helix is the most common. What bond stabilizes this helix? A. Hydrogen bond B. Peptide bond C. Phosphodiester bond D. Hydrophobic bond E. Ionic bond

A. Hydrogen bond

17. What protein structures reverse the direction of a polypeptide chain, helping it form a compact, globular shape? A. Alpha-helices B. Beta-sheets C. Beta-bends D. All of these E. Ionic bond

C. Beta-bends

18. What specialized groups are required for the proper folding of many species of proteins? A. Chaperones B. Heat shock proteins C. Beta bends D. A and B E. A and C

D. A and B

19. Many proteins consist of a single polypeptide chain, and are defined as monomeric proteins. However, others may consist of two or more polypeptide chains that may be structurally identical or totally unrelated. These statements describe what protein structure? A. Primary structure B. Secondary structure C. Tertiary structure D. Quaternary structure E. None of these

D. Quaternary structure

20. What protein is misfolded in Creutzfeldt-Jakob disease? A. Prion B. Glutamine stretches C. Beta-globin D. Beta-amyloid E. None of these

A. Prion

21. What are the two most abundant hemeproteins in humans? A. Hemoglobin and myoglobin B. Hemoglobin and cytochrome oxidase C. Hemoglobin and catalase D. Cytochrome and catalase E. All of these

A. Hemoglobin and myoglobin

22. The complex of protoporphyrin IX and ferrous iron is termed as: A. Heme B. Hemoglobin C. Transferrin D. Ferritin E. Myoglobin

A. Heme

23. What is the hemeprotein found in heart and skeletal muscles which functions both as a reservoir for oxygen and as an oxygen carrier that increases the rate of transport of oxygen within the muscle cell? A. Hemoglobin B. Myoglobin C. Actin D. Myosin E. Keratin

B. Myoglobin

24. This is found exclusively in red blood cells (RBCs) where its main function is to transport oxygen (O2) from the lungs to the capillaries of the tissues. A. Myoglobin B. Keratin C. Collagen D. Hemoglobin E. Myosin

D. Hemoglobin

25. The major hemoglobin in adults comprising four polypeptide chains held together by noncovalent interactions. A. Hemoglobin A B. Hemoglobin T C. Hemoglobin R D. Hemoglobin F E. Hemoglobin C

A. Hemoglobin A

26. These are hereditary hemolytic diseases in which an imbalance occurs in the synthesis of globin chains. A. Sickle cell anemia B. Thalassemia C. Microcytic anemia D. Iron deficiency anemia E. Hyperchromic anemia

B. Thalassemia

27. Oxidation of the heme component of hemoglobin to the ferric ion (Fe3+) state forms: A. Carboxyhemoglobin B. Methemoglobin C. Ferritin D. Transferrin E. Porphyrin

B. Methemoglobin

28. Collagen and elastin are examples of: A. Fibrous proteins B. Globular proteins C. Albumins D. Metalloproteins E. Enzymes

A. Fibrous proteins

29. What is the most abundant protein in the human body? A. Keratin B. Elastin C. Collagen D. Hemoglobin E. Myoglobin

C. Collagen

30. Fibril-forming collagens include all of the following EXCEPT: A. Type I B. Type II C. Type III D. Type IV E. None of these

D. Type IV

31. Which of the following pairs is correct about collagen types? A. Type I: Fibril associated collagen B. Type II: Network forming collagen C. Type III: Fibril-forming collagen D. Type IV: Fibril forming collagen E. Type IX: Network forming collagen

C. Type III: Fibril-forming collagen

32. Collagen is rich in _____ and _____, both of which are important in the formation of the triple-stranded helix. A. Proline and leucine B. Proline and isoleucine C. Proline and glycine D. Proline and histamine E. Proline and tyrosine

C. Proline and glycine

33. A heterogeneous group of generalized connective tissue disorders that result from inheritable defects in the metabolism of fibrillar collagen molecules, and can result from a deficiency of collagen processing enzymes (for example, lysyl hydroxylase or procollagen peptidase), or from mutations in the amino acid sequences of collagen types I, III or V. A. Ehlers-Danlos syndrome B. Von Gierke's syndrome C. Osteogenesis imperfecta D. Huntington's disease E. Hurler's syndrome

A. Ehlers-Danlos syndrome

34. A connective tissue protein with rubber-like properties in tissues such as the lung. A. Collagen B. Keratin C. Elastin D. Albumin E. Hemoglobin

C. Elastin

35. A connective tissue disorder characterized by impaired structural integrity in the skeleton, the eye, and the cardiovascular system. A. Hurler's disease B. Marfan syndrome C. Rheumatoid arthritis D. Gaucher's disease E. Huntington's disease

B. Marfan syndrome

36. Lactate-pyruvate conversion is possible due to the presence of lactate dehydrogenase. What enzyme category does lactate dehydrogenase belong to? A. Hydrolase B. Oxidoreductase C. Transferases D. Lyases E. Isomerases

B. Oxidoreductase

37. Which of the following pairs is incorrect about the intracellular location of the biochemical pathways? A. Lysosome: Macromolecular degradation B. Nucleus: Protein synthesis C. Cytosol: Glycolysis D. Mitochondria: Fatty acid oxidation E. Cytosol: HMP shunt

B. Nucleus: Protein synthesis

38. What is the process of recycling proteins into their constituent amino acids for reuse by the cell? A. Protein catabolism B. Protein turnover C. Protein synthesis D. Protein denaturation E. Protein degradation

B. Protein turnover

39. A large protein that may contain two or more regions of the polypeptide chain that individually have a compact folded structure is called: A. Domains B. Chaperones C. Residues D. Proteasome E. None of these

A. Domains

40. The following are true about amino acids, EXCEPT: A. They may polymerize to form polypeptides B. They serve as precursors for other small biomolecules C. They may be oxidized to serve as an energy source for the cell D. They act as building blocks of fatty acids E. None of these

D. They act as building blocks of fatty acids

41. Of the 20 important amino acids, which is NOT optically active (achiral)? A. Proline B. Lysine C. Arginine D. Leucine E. Glycine

E. Glycine

42. The following amino acids contain sulfur on their structure, EXCEPT: A. Cysteine B. Methionine C. Tyrosine D. Leucine E. Glycine

C. Tyrosine

43. Which of the following amino acids does not contain a benzene ring in its structure? A. Tyrosine B. Phenylalanine C. Tryptophan D. All of these E. None of these

C. Tryptophan

44. RNAs with catalytic activity are called: A. Apoenzymes B. Zymogens C. Proenzymes D. Ribozymes E. Holoenzymes

D. Ribozymes

45. The number of molecules of substrate converted to product per enzyme molecule per second: A. Bloom strength B. Turnover number C. Saponification number D. Conformational change E. None of these

B. Turnover number

46. Which of the following is incorrectly paired? A. Holoenzyme: active enzyme B. Apoenzyme: inactive enzyme C. Cofactor: inorganic molecule D. Coenzyme: Small organic molecule E. Prosthetic group: transiently associated with the enzyme

E. Prosthetic group: transiently associated with the enzyme

47. Which of the following is false about the kinetic order of enzymes? A. When the substrate concentration [S] is much lesser than the Km, the rate of reaction is first order. B. When [S] is much greater than Km, the velocity is constant and equal to Vmax. C. When [S] is much less than Km, the velocity of the reaction is approximately proportional to the substrate concentration. D. When the substrate concentration [S] is greater than the Km, the rate of reaction is zero order. E. None of these

E. None of these

48. Irreversible inhibitors bind to enzymes through what bond? A. Covalent bond B. Ionic bond C. Hydrogen bond D. Hydrophobic bond E. Sigma and pi bonds

A. Covalent bond

49. Which of the following is true about competitive inhibition? A. The reaction of the substrate and inhibitor is irreversible B. Substrate binds to active site, inhibitor binds to allosteric site C. Inhibitor is covalently bonded to the enzyme D. The reaction is not surmountable E. None of these

E. None of these

50. This occurs when inhibitor and substrate bind at different sites on the enzyme. A. Competitive inhibition B. Non-competitive inhibition C. Functional inhibition D. Chemical inhibition E. Physiological inhibition

B. Non-competitive inhibition

51. Enzymes are often measured in clinical diagnosis. Which of the following is correlatable to an elevated alanine aminotransferase (ALT)? A. Brain tumor B. Hepatic damage C. Prostate cancer D. Colon cancer E. Eye injury

B. Hepatic damage

52. ADH requires NAD+ for catalytic activity. In the reaction catalyzed by ADH, an alcohol is oxidized to an aldehyde as NAD+ is reduced and dissociates from the enzyme. The NAD+ is functioning as a (an): A. Apoenzyme B. Coenzyme-cosubstrate C. Coenzyme-prosthetic group D. Cofactor E. Eye injury

B. Coenzyme-cosubstrate

53. Which of the following is not true about the digestion of protein? A. Protein digestion begins in the mouth B. The digestion of protein may be due to gastric acid secretion C. Pancreatic enzymes aid in the digestion of protein D. Aminopeptidases digest oligopeptides in the small intestine E. None of these

A. Protein digestion begins in the mouth

54. What is the most common genetic error of amino acid transport? A. Phenylketonuria B. Alkaptonuria C. Cystinuria D. Methemoglobinemia E. Pellagra

C. Cystinuria

55. A disease of malabsorption resulting from immune-mediated damage to the small intestine in response to ingestion of gluten A. Cystic fibrosis B. Celiac disease C. Ulcerative disease D. Crohn's disease E. Conn's disease

B. Celiac disease

56. What is the first step of metabolic catabolism of amino acids? A. Conjugation B. Transamination C. Transpeptidation D. Hydrolysis E. Reduction

B. Transamination

57. All amino acids participate in transamination at some point in their catabolism, EXCEPT: A. Lysine B. Threonine C. Tryptophan D. A and B E. A and C

D. A and B

58. What is the only amino acid that undergoes rapid oxidative deamination? A. Lysine B. Tyrosine C. Glutamate D. Tryptophan E. Ornithine

C. Glutamate

59. In the transport of ammonia from the peripheral tissues to the liver, which of the following mechanisms is true? A. Glutamine is transported in the blood to the liver where it is cleaved by glutaminase to produce glutamate and free ammonia B. Alanine is transported by the blood to the liver, where it is converted to pyruvate by transamination C. Transamination of pyruvate to alanine is required to allow transport of alanine to the liver. D. A and B E. All of these

E. All of these

60. Where is the production and excretion site of urea? A. Liver for production, kidney for excretion B. Muscle for production, kidney for excretion C. Liver for production, mammary gland for excretion D. Liver for both production and excretion E. None of these

A. Liver for production, kidney for excretion

61. What amino acid is the immediate precursor of both ammonia and aspartate nitrogen in urea synthesis? A. Glutamate B. Aspartate C. Pyruvate D. Oxaloacetate E. Lactate

A. Glutamate

62. The synthesis of urea is located on which cellular sites? A. Mitochondria B. Cytosol C. DNA D. A and B E. All of these

D. A and B

63. Ammonia is produced by all tissues during the metabolism of a variety of compounds. However, the level of ammonia in the blood must be kept really low, because elevated concentrations (Hyperammonemia) are toxic to what part of the body system? A. Autonomic nervous system B. Central nervous system C. Integumentary system D. Skeletal system E. Digestive system

B. Central nervous system

64. The following are potential sources of ammonia, EXCEPT: A. Glutamine B. Monoamines C. Purines D. Pyrimidines E. Resorcinol

E. Resorcinol

65. What two nitrogen-containing compounds are incorporated into the urea cycle? A. Alanine and glutamate B. Glutamine and alanine C. Aspartate and ammonia D. Ammonia and aspartate E. Alanine and arginine

D. Ammonia and aspartate

66. Evaluate the two statements. (1) Essential amino acids must be obtained from diet in order for normal protein synthesis to occur (2) Essential amino acids are produced from the intermediates of metabolism of protein. A. Only 1 is correct B. Only 2 is correct C. Both are correct D. Both are incorrect

A. Only 1 is correct

67. Amino acids whose catabolism yields either acetoacetate or one of its precursors (Acetyl CoA or acetoacetyl CoA) are termed as: A. Glucogenic amino acids B. Ketogenic amino acids C. Metabotropic compounds D. Amphoteric amino acids E. Zwitterionic amino acids

B. Ketogenic amino acids

68. Which of the following amino acids doesn't belong to the group (exclusively ketogenic vs both glucogenic/ketogenic)? A. Tyrosine B. Isoleucine C. Phenylalanine D. Lysine E. Tryptophan

D. Lysine

69. The amino acids leucine, isoleucine and valine are: A. Branched-chain amino acids B. Essential amino acids C. Aromatic amino acids D. A and B E. C and D

D. A and B

70. Succinyl CoA, a Krebs cycle intermediate, may be derived from the degradation of the following, EXCEPT: A. Valine B. Isoleucine C. Threonine D. Asparagine E. None of these

D. Asparagine

71. The most common clinically encountered inborn error of amino acid metabolism A. Tyrosinemia type I B. Phenylketonuria C. Albinism D. Maple syrup urine disease E. Pellagra

B. Phenylketonuria

72. Tyrosine is needed in the synthesis of the following, EXCEPT: A. Tissue protein B. Melanin C. Catecholamines D. Fumarate E. Phenylacetate

E. Phenylacetate

73. The following are clinical characteristics of classical phenylketonuria: A. Elevated phenylalanine B. CNS symptoms C. Hypopigmentation D. Blue eyes E. All of these

E. All of these

74. A disease which is characterized by feeding problems, vomiting, dehydration, severe metabolic acidosis. This condition is due to partial or complete deficiency in the branched-chain alpha-keto acid dehydrogenase. A. Phenylketonuria B. Maple syrup urine disease C. Pellagra D. Albinism E. Hypopigmentation

B. Maple syrup urine disease

75. Albinism refers to a group of conditions in which a defect in tyrosine metabolism results in a deficiency in the production of: A. Melatonin B. Melanin C. Melanocyte D. All of these E. None of these

B. Melanin

76. The homocystinurias are a group of disorders involving defects in the metabolism of homocysteine. The most common cause of homocystinuria is a defect in the enzyme cystathionine beta-synthase. Patients can be responsive (or nonresponsive) to oral administration of the vitamin coenzyme of cystathionine beta-synthase. What vitamin is referred to in this condition? A. Thiamine B. Niacin C. Pantothenic acid D. Pyridoxine E. Biotin

D. Pyridoxine

77. Which of the following amino acids should be avoided by patients with alkaptonuria? A. Phenylalanine B. Tyrosine C. Alanine D. A and B E. B and C

D. A and B

78. Which of the following pairs (precursor -> product) is incorrect? A. Histidine -> histamine B. Tryptophan -> serotonin C. Arginine -> nitric oxide D. Methionine -> purine/pyrimidine E. Tyrosine -> dopamine

D. Methionine -> purine/pyrimidine

79. Which one of the following statements concerning a 1-week-old male infant with undetected classic phenylketonuria is correct? A. Tyrosine is a nonessential amino acid for the infant B. High levels of phenylpyruvate appear in his urine C. Therapy must begin within the first year of life D. A diet devoid of phenylalanine should be initiated immediately E. When the infant reaches adulthood, it is recommended that diet therapy be discontinued

B. High levels of phenylpyruvate appear in his urine

80. Which cyclic organic molecule is present in the structure of porphyrin? A. Indole B. Pyrrole C. Quinolone D. Pyridine E. Piperidine

B. Pyrrole

81. The most prevalent metalloporphyrin in humans is heme. It serves as a prosthetic group for: A. Cytochrome B. Hemoglobin C. Peroxidase D. All of these E. A and B

D. All of the specified metalloproteins

82. Inherited (or occasionally acquired) defects in heme synthesis may result in: A. Porphyria B. Phenylketonuria C. Methemoglobinemia D. Lead poisoning E. Albinism

A. Porphyria

83. What is the approximate number of days red blood cells remain in circulation before degradation? A. 40 days B. 80 days C. 120 days D. 150 days E. 365 days

C. 120 days

84. Bilirubin and biliverdin are examples of: A. Bile salts B. Bile pigments C. Bile duct D. All of these E. None of these

B. Bile pigments

85. Certain anionic drugs, such as salicylates and sulfonamides, can displace bilirubin from albumin, permitting bilirubin to enter the central nervous system. This causes potential for neural damage in infants known as: A. Saint Louis Encephalitis B. Systemic Lupus Erythematosus C. Steven-Johnson syndrome D. Kernicterus E. All of these

D. Kernicterus

86. Van den Bergh reaction determines the concentration of: A. Protein B. Bilirubin C. Heme D. Glucose E. Cholesterol

B. Bilirubin

87. The following are catecholamines, EXCEPT: A. Epinephrine B. Norepinephrine C. Acetylcholine D. Dopamine E. None of these

C. Acetylcholine

88. What organic pigment protects underlying cells from the harmful effects of sunlight? A. Melanin B. Keratin C. Collagen D. Catecholamines E. Heme

A. Melanin

89. The 4D symptoms of pellagra include: diarrhea, dermatitis, dementia and death. This is due to the deficiency of: A. Niacin B. Tyrosine C. Tryptophan D. A and C E. A and B

D. A and C

90. Tryptophan: I. One-letter representation is "W" II. Non-polar molecule III. Deficiency of which can cause Hartnup disease IV. The structure contains an indole side chain A. I & II are correct B. I, II, and III are correct C. II and III are correct D. I, II, III and IV are correct E. I, II, III and IV incorrect

C. II and III are correct

91. What is the isoelectric point (pI) of arginine? A. 7.87 B. 5.55 C. 10.75 D. 7.3 E. 10.76

E. 10.76

92. Estimate the isoelectric point of alanine (pK1=2.34, pK2=9.69). A. 2 B. 9 C. 6 D. 5 E. 7

C. 6

93. Which of the following secondary derived proteins has the highest molecular weight characteristic? A. Proteoses B. Peptones C. Peptides D. A and B E. B and C

A. Proteoses

94. Tyrosine can be detected by: A. Xanthoproteic test B. Millon's test C. Sakaguchi test D. A, B and C E. A and B

E. A and B

95. Hopkins-Cole reaction gives a positive result in: A. Gelatin B. Collagen C. Tryptophan D. A and B E. B and C

C. Tryptophan

96. Which of the following is an essential amino acid in man? A. Tyrosine B. Proline C. Aspartate D. Threonine E. Serine

D. Threonine

97. Which of the following amino acids is NOT basic? A. Lysine B. Arginine C. Ornithine D. Glutamine E. Histidine

D. Glutamine

98. Which of the following bonds is not affected by denaturation due to its high stability? A. Disulfide bond B. Peptide bond C. Hydrogen bond D. Ionic bond E. None of these

B. Peptide bond

99. Arginine and histidine are: A. Essential amino acids B. Non-essential amino acids C. Semi-essential amino acids D. Acidic amino acids E. Aromatic amino acids

C. Semi-essential amino acids

100. A tripeptide involved in cellular oxidation-reduction, and is required for maintaining the integrity of RBC and lens of eyes. A. Glutathione B. Vasopressin C. Enkephalin D. Oxytocin E. Retinol

A. Glutathione