1 point each 1. The strongest non-covalent intermolecular forces are: A) van der Waals forces D) Dipole-dipole interactions B) London dispersion forces E) Ionic interactions C) Hydrogen bonds 2. Under what conditions would an amine group be mostly charged? A) pH = pK B) pH pK 3. W

BCH 369 Practice Exam 1 Fall 2016 Name: __________________________________________ eID ________________ Section I (20 points): 1 point each 1. The strongest non-covalent intermolecular forces are: A) van der Waals forces D) Dipole-dipole interactions B) London dispersion forces E) Ionic interactions C) Hydrogen bonds 2. Under what conditions would an amine group be mostly charged? A) pH = pK B) pH < pK C) pH > pK 3. Which of the following could be unicellar? A) Prokaryotes C) Either prokaryotes or eukaryotes B) Eukaryotes D) Neither prokaryotes nor eukaryotes 4. In SDS gel electrophoresis A) proteins are separated based on their molecular weight B) only proteins with aromatic amino acids may be separated C) the largest proteins move the farthest D) all of the above 5. Which of the following is NOT an element of protein secondary structure? A) Alpha helix B) Peptide bond C) Beta sheet D) Polypeptide loop E) All of the above are elements of protein secondary structure. 6. Which of the following statements is TRUE about the way that hemoglobin and myoglobin bind oxygen? A) Hemoglobin has a linear oxygen saturation curve while myoglobin has a hyperbolic curve. B) Hemoglobin has a sigmoidal oxygen saturation curve while myoglobin has a linear curve. C) Hemoglobin has a hyperbolic oxygen saturation curve while myoglobin has a linear curve. D) Hemoglobin has a sigmoidal oxygen saturation curve while myoglobin has a hyperbolic curve E) None of the above is true. 7. What is the [H+] for saliva (pH ~6.6)? A) 2.5 x 10-7 M B) 3.2 x 10-6 M C) 4.0 x 106 M D) 2.5 x 107 M E) 4.0 x 10-6 M 8. Which of the following assembles by association of multiple protofilaments? A) Myosin B) Actin C) Tubulin D) Keratin E) Collagen Page 1 9. Which of the molecules below contains a carboxylate group? (a) (b) (c) (d) A) (a) only D) (a), (c), and (d) B) (b) only E) All (a-d) C) (a) and (b) 10. Which of the following proteins contain a high percentage of a modified Pro residue? A) Keratin B) Collagen C) Tubulin D) Actin E) Myosin 11. In order to find planets that may host life, Astrophysicists analyze distant solar systems using light emission spectrometry in which light is scattered through a prism and distinct spectral lines reveal the elements from which these lines are generated. If trying to find potential life-hosting worlds, which elements would you expect astrophysicists are looking for in highest abundance in these distant solar systems? A) O, Ca, Na, N, H B) O, C, N, H C) Si, N, O, Fe, H D) H, O, S, He, N 12. Disulfide bonds form between two residues of which amino acid? A) Met B) Ser C) Asn D) Thr E) Cys 13. Which of the following does NOT exhibit quaternary structure? A) Hemoglobin B) Collagen C) Tubulin D) Myoglobin E) Keratin 14. Which amino acid would most likely associate with the inner part of the lipid bilayer? A) V B) E C) H D) D E) K 15. What term is used to describe the exclusion of nonpolar substances from an aqueous solution? A) nonpolar effect D) oil droplet effect B) lipid effect E) amphiphilic effect C) hydrophobic effect 16. The tertiary structures of myglobin, α-hemoglobin and β-hemoglobin are nearly identical and are therefore nearly identical in primary structure. A) True B) False 17. What is the sign of the entropy change when dry ice sublimates? A) Positive B) Negative C) No change Page 2 18. Which of the following molecules contains the most oxidized form of carbon? A) acetaldehyde D) ethylene B) ethanol E) carbon dioxide C) acetic acid 19. Which of the following techniques is useful in determining the primary structure of peptides? A) Ion exchange chromatography D) Edman sequencing B) X-ray crystallography E) Both C and D C) Mass spectrometry 20. Using what you have learned about acidic functional groups, which form of this compound is likely to predominate in the cell at pH 7.4? A) Pyruvic acid B) Pyruvate C) Neither will predominate — there will be equal amounts of each Section II (62 points): 2 points each 21. Beta sheets consist of tight, right hand turns which causes the protein to fold back onto itself and allows for the characteristic hydrogen bonding. Which amino acids would likely be found at these turning points? A) E, K B) G, P C) L, I D) R, K E) S, T 22. What is the pH of a solution of 1.0 x 10-10 NaOH? A) 4 B) 7 C) 8 D) -4 E) 14 23. What types of bonds are present in DNA? A) Peptide bonds D) Both A and B B) Phosphodiester bonds E) Both B and C C) Glycosidic bonds 24. What level of protein structure contains the information needed for proper protein folding? A) Primary B) Secondary C) Tertiary D) Quaternary E) A and B 25. Given the information below, which protein will migrate to the cathode at pH 8.0? Protein pI Myoglobin 6.8 Cytochrome c 9.3 Carbonic anhydrase 4.9 A) Myoglobin B) Cytochrome c C) Carbonic anhydrase Page 3 26. Calculate the ratio of imidazole to the imidazolium ion (pK 7.00) in a solution of pH 7.4 (structure below). A) 2.5:1 B) 1:2.5 C) 0.33:1 D) 1:0.33 27. Enkephalin is an endogenous opioid peptide neurotransmitter. Based on the structure of the peptide at physiological pH (below), what is the sequence of the peptide? A) T-G-G-P-L B) Y-G-G-F-L C) F-G-A-Y-I D) Y-A-A-Y-I E) W-G-G-I-V 28. What is the net charge on the following peptide at pH 5? V-E-R-Y-H-A-R-M-F-Y-L A) +2 B) +1 C) 0 D) -1 E) -2 29. Which of the following proteins contain polypeptide chains that associate in a coiled-coil interaction? A) Actin B) Keratin C) Myosin D) A and B E) B and C 30. You are given data that shows the ΔG of the reaction below to be approximately -31.5 kJ/mol. In the laboratory, you measure an enthalpy value of -4.3 kJ/mol and an entropy value of +73.4 J/mol. At what temperature must this reaction take place in order to reach the experimentally determined ΔG value? Phosphoenolpyruvate + ADP + Pi –> Pyruvate + ATP A) 100oC B) 371oC C) 298K D) 371K E) 97K 31. How many H-bond acceptor atoms are present in the molecule below? (Note: These are individual atoms NOT groups.) A) 2 B) 3 C) 4 D) 5 E) 6 32. Which of the major types of biomolecules is never found in a polymeric form? A) amino acids D) lipids B) carbohydrates E) none of the above C) nucleotides Page 4 33. According to the table below, which of the listed elements would likely be the strongest H-bond acceptor? A) C B) F C) H D) N E) O 34. Rank the following compounds with increasing solubility in water. A) (a) < (d) < (c) < (b) < (e) D) (a) < (d) < (d) < (c) < (b) B) (d) < (a) < (e) < (b) < (c) E) (d) < (e) < (a) < (b) < (c) C) (d) < (e) < (a) < (c) < (b) 35. In the following reaction of succinate to form fumarate A) Succinate is oxidized and FAD is reduced D) Succinate is reduced and FAD is reduced B) Fumarate is oxidized and FAD is reduced E) Succinate is oxidized and FAD is oxidized C) Succinate is reduced and FAD is oxidized Page 5 36. Of the following amino acids, which contains an alcohol? A. B. C. D. A) a D) d B) b E) all of the above C) c 37. If the following two reactions were coupled, what would be the ΔG for the overall exergonic reaction? ATP + H2O → ADP + Pi ΔG = -31 kJ/mol Glucose + Pi → glucose-1-phosphate + H2O ΔG = 21 kJ/mol A) -52 kJ/mol D) 52 kJ/mol B) -10 kJ/mol E) none of the above C) 10 kJ/mol 38. Which of the following is an example of an amphipathic molecule? A) adenine, a base found in nucleic acids D) palmitic acid, a fatty acid B) glucose, a monosaccharide E) none of the above C) serine, an amino acid 39. The structure of acetylsalicylic acid (aspirin) is shown below. Is aspirin more likely to be absorbed (pass through a lipid membrane) in the stomach (pH ~2) or in the small intestine (pH ~8)? A) Stomach C) Absorbed in both stomach and small intestine B) Small intestine 40. What is the N-terminal residue of the peptide AYSDG? A) glutamic acid D) alanine B) glycine E) none of these choices C) aspartic acid Page 6 41. The following structure is an amino acid derivative found in collagen structures. Based on your knowledge of amino acid structure, what is the name of this derivative? A) Hydroxylysine D) Hydroxyproline B) Lipocysteine E) Selenocysteine C) Pyrrolysine 42. For marine mammals that spend a significant amount of time under water, retaining sufficient oxygen in muscle tissue is essential for their survival. Based on your understanding of the oxygen binding functions of myoglobin (Mb) and hemoglobin (Hb), how would you expect the ratio of Mb to Hb to compare between humans and marine mammals? A) The ratio of myoglobin to hemoglobin in humans and marine mammals would be identical. B) The ratio of myoglobin to hemoglobin would be higher in humans than in marine mammals. C) The ratio of myoglobin to hemoglobin would be higher in marine mammals than in humans. D) Not enough information to tell 43. Phosphoric acid (H3PO4) has 3 ionizable protons (pK1 2.15, pK2 6.82, pK3 12.38). Which two phosphate species would be used to prepare a buffer solution at pH 11? A) H3PO4 and H2PO4- D) H2PO4- and PO43- B) H2PO4- and HPO42- E) H3PO4 and HPO42- C) HPO42- and PO43- 44. Why is it important that the heme prosthetic group be buried in a hydrophobic pocket in O2-binding proteins? A) The heme group is entirely hydrophobic and therefore cannot be solvent exposed. B) O2 is uncharged and hydrophobic and therefore needs this type of environment in order to bind. C) The heme iron is readily oxidized to Fe3+, which cannot bind O2. D) The heme group would bind H2O instead of O2 if it were solvent exposed. 45. In humans, Sporatic Fatal Insomnia (sFI) is a disease characterized by difficulty falling asleep, difficulty walking, gradual weight loss and excessive tear production. sFI rapidly progresses to the loss of consciousness and eventually death. sFI is thought to result from the aggregation of misfolded proteins in the cell. Which of the following interactions contributes the most to the aggregation of these protein structures? A) van der Waals D) disulfide B) ionic E) hydrogen bonding C) covalent Page 7 46. Bisphosphoglycerate promotes the oxy-state of hemoglobin. A) True B) False 47. Hundreds of hemoglobin variants are known, but one of the better-known variants is sickle-cell hemoglobin (Hb S). It is the aggregation of deoxy-Hb S that results in the sickling of the cell. The protozoan that causes malaria, Plasmodium falciparum, slightly decreases the pH of the red blood cells it infects. Are Plasmodium-infected cells more or less likely to undergo sickling in individuals with the Hb S variant? A) More likely B) Less likely C) Equally likely 48. What type of interactions are responsible for the characteristic strength of keratin fibers? A) van der Waals D) A and B B) Disulfide bonds E) A, B and C C) Hydrogen bonds 49. Collagen molecules contain cross-links of the amino acid side chains of A) C B) Y C) S D) K E) P 50. What is the prominent type of secondary structure observed in myoglobin? A) β-helices D) antiparallel β-sheets B) α-bends E) α-helices C) parallel β-sheets 51. Each myosin head contains a binding site for _____ and a binding site for _____. A) tubulin; GTP D) actin; ATP B) another myosin molecule; ATP E) none of the above C) kinesin; GTP Section III (18 points): 3 points each 52. Phosphoenolpyruvate donates a phosphate groups to ADP to produce pyruvate and ATP. The ΔG value for this reaction at 25oC is -63 kJ/mol and the value of ΔS is 190 J/K-mol. What is the value of ΔH and is the reaction exothermic or endothermic? A) +6.4 kJ/mol, exothermic D) +119.6 kJ/mol, endothermic B) -6.4 kJ/mol, exothermic E) -119.6 kJ/mol, exothermic C) -119.6 kJ/mol, endothermic 53. Like all equilbrium constants, the value of KW is temperature dependent. KW is 1.47 x 10-14 at 30oC. What is “neutral” pH at this temperature? A) 7.00 B) 6.92 C) 13.8 D) 6.00 E) 14.0 54. One liter of 0.150 M Tris buffer (pK 8.30) is prepared and adjusted to pH 8.40. What is the pH when 2.00 mL of 3.00 M HCl is added to this buffer? A) 8.05 B) 7.05 C) 8.29 D) 8.75 E) 7.85 Page 8 55. About 24 His residues in hemoglobin (Hb) are involved in binding protons produced by cellular metabolism. In this manner, Hb contributes to buffering in the blood. One important contributor is His146 on the β chain of Hb, whose side chain is in close proximity to the side chain of Asp94 in the deoxy form of Hb but not in the oxy form. What kind of interaction occurs between Asp94 and His146 in deoxy-Hb? In what way does the proximity of Asp94 alter the pK of His? A) Asp94 & His146 form a hydrogen bond; Asp94 increases the pK of His146 B) Asp94 & His146 form an ion pair; Asp94 decreases the pK of His146 C) Asp94 & His146 form an ion pair; Asp94 increases the pK of His146 D) Asp94 & His146 form an dipole-dipole pair; Asp94 decreases the pK of His146 E) Asp94 & His146 form a hydrogen bond; Asp94 decreases the pK of His146 56. You isolate a solution of three unknown proteins X, Y, and Z from a cell, but you wish to study each protein individually. Given the following molecular weights and isoelectric points, which would be the best method to elute ONLY protein Z FIRST from the solution? Protein MW(D) pI X 45,000 8.0 Y 45,150 6.3 Z 44,950 4.2 A) Use size exclusion chromatography to separate the proteins by molecular weight. B) Use DHEA-cellulose ion exchange chromatography beginning at pH 9.0 and gradually lower the pH to 5.2. C) Use CM-cellulose ion exchange chromatography beginning at pH 9.0 and gradually lower the pH to 5.2. D) Use CM-cellulose ion exchange chromatography beginning at pH 3.2 and gradually raise the pH to 5.2. 57. Which of the following correctly describes the sequence of events in the kinesin reaction cycle? For simplicity, the two heads are referred to as head 1 and head 2. Head 1 starts as the leading head. A) head 1 releases tubulin, ATP binds to head 1, head 2 swings forward, head 2 binds to tubulin, ADP release from head 2, ATP hydrolysis in head 1 B) ATP binds to head 1, head 2 swings forward, ADP release from head 2, ATP hydrolysis in head 1, head 2 binds to tubulin, head 1 releases tubulin C) ATP binds to head 1, head 2 swings forward, head 2 binds to tubulin, ATP hydrolysis in head 1, ADP release from head 2, head 1 releases tubulin D) ATP binds to head 1, head 2 swings forward, head 2 binds to tubulin, ADP release from head 2, ATP hydrolysis in head 1, head 1 releases tubulin E) none of the above Page 9 Answer Key – PracticeExam1_Fa16 1. E 2. B 3. C 4. A 5. B 6. D 7. A 8. C 9. D 10. B 11. B 12. E 13. D 14. A 15. C 16. B 17. A 18. E 19. E 20. B 21. B 22. B 23. E 24. A 25. B 26. A 27. B 28. A 29. E 30. D 31. D 32. D 33. B 34. B 35. A 36. A 37. B 38. D 39. A 40. D 41. D 42. C 43. C Page 10 44. C 45. A 46. B 47. A 48. D 49. D 50. E 51. D 52. B 53. B 54. C 55. C 56. D 57. D Page 11

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