exam1_s14

CH 369 Exam 1 February 6, 2014Name: __________________________________________ eID ________________

Helpful Equations:

degrees K = 273 + C

Section I (32 points): 1 point each

1. Which of the following would be the strongest acid? A) formic acid, pK=3.75 B) succinic acid, a diprotic acid with pK=4.21 and 5.64 C) acetic acid, pK=4.76 D) ammonium ion, pK=9.25 E) cannot be determined from the given information

2. Which of the following amino acids has a nonpolar side chain? A) Ser D) Asn B) Val E) none of these choices C) Lys

3. Bone and tendons contain _____ while hair and nails contain _____. A) collagen; keratin D) collagen; actin B) actin; keratin E) tubulin; keratin C) tubulin; collagen

4. -helices and -sheets comprise ___ structure. A) primary D) quaternary B) secondary E) none of these choices C) tertiary

5. Which amino acid is critical for crosslinking of keratin fibers? A) Ser B) Lys C) His D) Cys E) Gln

6. At a pH above its pKa, the phenolic group of tyrosine is ___. A) protonated and neutral D) deprotonated and negatively charged B) protonated and positively charged E) none of these choices C) deprotonated and neutral

7. Which of the 20 standard amino acids is optically inactive? A) Arg B) Pro C) Ile D) Gly E) Cys

8. Which of the following would have the lowest melting point? A) NH3 B) CH4 C) H2O

Scrambled version A Page 1

9. What is the conjugate acid of H2PO4-?

A) HPO42- D) PO43-

B) H2PO4 E) none of the above C) H3PO4

10. 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

11. Which of the following would be a proper designation of the deoxy position on DNA? A) 3' (3 prime) B) 3 C) 2' (2 prime) D) 2 E) 1

12. If the following two reactions were coupled, what would be the G for the overall exergonic reaction?ATP + H2O ADP + Pi G = -31 kJ/mol

Glucose + Pi glucose-1-phosphate + H2O G = 21 kJ/mol

A) -52 kJ/mol D) 52 kJ/mol B) -10 kJ/mol E) none of the above C) 10 kJ/mol

13. The most important buffering system for maintaining proper blood pH is: A) the charges on the amino acids B) the bicarbonate buffer system of CO2, carbonic acid, and bicarbonate C) phosphate groups of serum phosphoproteins D) none of the above E) all of the above

14. A protein that consists of a single polypeptide chain will lack which level of protein structure? A) Primary B) Secondary C) Tertiary D) Quaternary E) Pentanary


15. What level of protein structure is characterized by the three dimensional structure of an entire polypeptide including all amino acid side chains?

A) primary D) quaternary B) secondary E) none of these choices C) tertiary

16. The Bohr effect describes a lowered O2-affinity of Hb when the pH _____. A) increases B) decreases

17. The higher the dielectric constant, the more ________ the compound. A) polar D) nonpolar B) negatively charged E) oxidized C) positively charged

18. Which RNA molecules are involved in the process of translation? A) mRNA B) tRNA C) rRNA D) A and C E) A, B and C

19. Which of the following is a simple statement of Chargaffs rules? A) A+G = C+T B) A = C C) C = T D) G = A

20. Heme is considered a _____. A) catalyst D) cofactor B) prosthetic group E) none of the above C) coenzyme

21. Which of the following is the most abundant structural element in the human body? A) nitrogen D) phosphorous B) carbon E) none of the above C) oxygen

22. What bonding interactions are broken during DNA denaturation? A) Covalent bonds D) B and C B) Hydrogen bonds E) A, B and C C) van der Waals interactions

23. The tertiary structures of myglobin, -hemoglobin and -hemoglobin are nearly identical and are therefore nearly identical in primary structure.

A) True B) False

24. Which of the following assembles by association of multiple protofilaments? A) myosin B) actin C) tubulin D) keratin E) collagen


25. What term describes the process of converting the information found in DNA into the sequence of a protein?

A) replication D) expression B) transcription E) none of the above C) translation

26. Which of the two proteins below has a longer neck region? A) myosin B) keratin C) kinesin D) collagen E) actin

27. Which of the following is an example of the hydrophobic effect? A) the lipid membrane of cells and organelles B) protein folding that places hydrophobic amino acids in the interior of the protein C) the separation of salad dressing D) oil sheens seen on the ocean following an oil spill E) all of the above

28. At physiological pH, all amino acids have at least ___ charged groups. A) 0 D) 3 B) 1 E) cannot be determined C) 2

29. The replication of DNA is made possible by the presence of _____ strands in the double helix of DNA. A) antiparallel D) genomic B) hydrogen bonded E) none of the above C) complementary

30. Which of the following amino acids has a thiol group in its side chain? A) Ser B) Asn C) Cys D) Tyr E) Met

31. Which of the following molecules contains the most oxidized form of carbon? A) acetaldehyde D) ethylene B) ethanol E) carbon dioxide C) acetic acid

32. In a muscle cell, what is the name for the bundles of myosin tails? A) cytoskeleton D) thin filaments B) thick filaments E) none of the above C) intermediate filaments

Section II (50 points): 2 points each

33. Which of the following statements regarding RNA is FALSE? A) The ribose in RNA contains an O atom that the ribose in DNA lacks. B) RNA does not form a 2-stranded double helix like DNA. C) Since RNA does not form a double helix, it tends to be linear in shape. D) RNA can form Watson-Crick base pairs with DNA.


34. Would DNA-binding proteins be more likely to associate with the major or the minor groove? A) Major groove B) Minor groove

35. Identify the amino acid structure below.

A) H B) I C) R D) D E) V

36. At pH ___, the pentapeptide Ala-Glu-His-Val-Cys would contain two positively charged groups and one negatively charged group.

A) 1 B) 3.5 C) 5 D) 7 E) 9

37. If a phosphate buffer (pK 6.82) was formulated such that its pH was 7.3, it would be best suited to buffer against _____. If instead, it was formulated such that its pH was 6.3, it would be best suited to buffer against _____.

A) acid; base B) acid; acid C) base; acid D) base; base E) a buffer with a pH that far from the pK would not be an effective buffer

38. Which of the biopolymers is correctly paired with its major function? A) protein: information encoding D) polysaccharide: energy storage B) nucleic acids: energy storage E) none of the above C) lipids: information encoding

39. Each kinesin head contains a binding site for _____ and a binding site for _____. A) tubulin; GTP D) actin; ATP B) another kinesin molecule; GTP E) tubulin; ATP C) myosin; ATP

40. Which allosteric effector has the greatest ability to stabilize the deoxy state of hemoglobin? A) BPG D) H+ B) CO2 E) all of the above have equal ability C) O2


41. A plot of the binding of oxygen to myoglobin as a function of pO2 gives a _____ shape; a similar plot for hemoglobin gives a _____ shape.

A) sigmoidal; sigmoidal D) hyperbolic; hyperbolic B) sigmoidal; hyperbolic E) hyperbolic; exponential C) hyperbolic; sigmoidal

42. If the following mixture of proteins was applied to a size-exclusion chromatography column, what would be the order of elution?

Proteins with molecular weights (kDa = kiloDalton = kg/mol): myoglobin (17.7 kDa) , hemoglobin (64.5 kDa) , lysozyme (14.3 kDa) and triose phosphate isomerase (57.4 kDa)

A) lysozyme, myoglobin, triose phosphate isomerase, hemoglobin B) triose phosphate isomerase, hemoglobin, lysozyme, myoglobin C) hemoglobin, myoglobin, lysozyme, triose phosphate isomerase D) hemoglobin, triose phosphate isomerase, myoglobin, lysozyme, E) cannot be determined

43. You are involved in the purification of Protein X with a pI of 6.0 using a buffer with a pH of 7.5. What type of resin would you choose to ensure initial binding of Protein X?

A) DEAE (pK ~10) B) CM (pK ~4)

44. Which of the following processes are involved in gene expression? A) Replication B) Transcription C) Translation D) Both B and C E) A, B and C

45. The pK of CH3CH2NH3+ is 10.7. Would the pK of FCH2CH2NH3+ be higher or lower? A) Higher B) Lower

46. Which of the following methods of amino acid sequence determination requires an unmodified amino terminus?

A) Mass spectroscopy D) Edman sequencing B) Ion exchange E) X-ray crystallography C) SDS-PAGE

47. Which of the following is an example of a conservative amino acid substitution? A) Ile Leu B) Ser Glu C) Phe Tyr D) Asp Gln E) Arg Cys

48. What is the fractional saturation (p50 = 2.8 torr) of myoglobin when pO2 = 15 torr? A) 0.65 D) 1.23 B) 0.58 E) None of the above are correct C) 0.84


49. What would be the resulting pH if one drop (0.05 ml) of 1.0 M HCl was added to one liter of pure water (assume pH 7.0)?

A) 2.7 D) 7.0 (there would be no significant change) B) 4.3 E) 9.7 C) 5.0

50. What is the net charge of the heptapeptide His-Ala-Cys-Asp-Ser-Glu-Asn at pH 7? A) -2 D) +1 B) -3 E) none of these choices C) 0

51. Do Chargaffs rules apply to RNA as well as to DNA? A) Yes B) No

52. For a globular protein that is found in the cytosol, ___ would most likely be found in the proteins interior while ___ would most likely be found on the surface.

A) Val; Phe D) Thr; His B) Leu; Ile E) none of these choices C) Leu; Ser

53. Which of the following would represent an increase in entropy? A) Ice freezes D) Sewing a garment B) Traffic congestion on highway E) Filing papers C) Dismissal of class when bell rings

54. Which of the following atoms would be considered a hydrogen bond donor in an -helix?

A) a D) d B) b E) none of these choices C) c

55. What is the pH of a solution that contains one part acetic acid and three parts sodium acetate? The pK for acetic acid is 4.76.

A) 5.24 B) 5.06 C) 4.46 D) 4.28 E) cannot be determined from the given information


Jason Tran

Jason Tran

56. Which of the following fibers is correctly paired with the protein that forms the fiber? A) microfilaments: actin D) intermediate filaments: keratin B) microtubule: tubulin E) all of the above C) extracellular support fibers: collagen

57. Which of the following explains the attractive forces between hydrophobic molecules in an aqueous solution?

A) in an aqueous environment, London dispersion forces between hydrophobic molecules become stronger

B) in an aqueous environment, London dispersion forces between hydrophobic molecules and water become stronger

C) since nonpolar molecules do not form hydrogen bonds with hydrogen bonds with water, they can form hydrogen bonds with other nonpolar molecules

D) there is no increase in attractive forces between nonpolar molecules in an aqueous environment E) none of the above

Section III (18 points): 3 points each

58. The oxygen-binding curves for normal hemaglobin (Hb A) and a mutant hemoglobin (Hb Great Lakes) are shown in the figure below. Which of the two hemoglobins: (i) has a higher affinity for oxygen when pO2 = 20 torr; and (ii) is most efficient at delivering oxygen from arterial blood (pO2 = 75 torr) to active muscle (pO2 = 20 torr)?

A) (i) Hb A; (ii) Hb A D) (i) same affinity; (ii) Hb A B) (i) Hb A; (ii) Hb Great Lakes E) (i) Hb Great Lakes; (ii) same efficiency C) (i) Hb Great Lakes; (ii) Hb A


59. Biochemists sometimes link a recombinant (modified) protein to green fluorescent protein (GFP). The fluorophore in GFP is a derivative of three consecutive amino acids that undergo cyclization of the polypeptide chain and an oxidation. Using the structure below, identify: (i) the three amino acid residues; and (ii) the bond that results from oxidation.

A) Met-Tyr-Ala; c D) Ser-Tyr-Gly; b B) Ser-Tyr-Gly; a E) Met-Tyr-Ala; a C) Ser-Phe-Gly; c

60. Based on the following Tm values, what can be said about these two DNA molecules: Strand A = 80C; Strand B = 100C?

A) Strand A has a higher percentage of adenine bases. B) Strand B has a higher percentage of cytosine bases. C) Strand B has stronger stacking interactions. D) All of the above

61. Rank the solubilities of the following amino acids in water at pH 7: W, R, S, V, T. A) V < W < T < S < R D) W < V < T < S < R B) W < V < S < T < R E) R < T < S < V < W C) V < W < S < T < R

62. Urea (NH2CONH2) dissolves readily in water. The beaker containing the dissolved compound is cold to the touch. What conclusions can you make about the sign of the (i) enthalpy change; and (ii) entropy change for this process?

A) + H; + S D) - H; + S B) - H; - S E) Cannot be determined C) + H; - S

63. A solution is made by mixing 25 mL of a stock solution of 2.0 M K2HPO4 (pK 6.82) and 50 mL of a stock solution of 2.0 M KH2PO4. The solution is diluted to a final volume of 200 mL. What is the final pH of the solution?

A) 7.12 B) 6.82 C) 6.52 D) 6.22 E) 7.42


Jason Tran

Jason Tran

Answer Key - Exam1_S14

1. A 2. B 3. A 4. B 5. D 6. D 7. D 8. B 9. C 10. A 11. C 12. B 13. B 14. D 15. C 16. B 17. A 18. E 19. A 20. B 21. B 22. D 23. B 24. C 25. D 26. A 27. E 28. C 29. C 30. C 31. E 32. B 33. C 34. A 35. B 36. B 37. A 38. D 39. E 40. A 41. C 42. D 43. A 44. D


45. B 46. D 47. A 48. C 49. B 50. A 51. A 52. C 53. C 54. A 55. A 56. E 57. D 58. C 59. B 60. D 61. D 62. A 63. C


Grabner, Gail

Grabner, GailB


Helpful Equations:

degrees K = 273 + C








Scrambled version B Page 1


A. B. C. D.












A) True B) False

















A) HPO42- D) PO43-








A) 1 B) 3.5 C) 5 D) 7 E) 9















A) 7.12 B) 6.82 C) 6.52 D) 6.22 E) 7.42





1. C 2. B 3. C 4. B 5. D 6. B 7. A 8. A 9. C 10. C 11. C 12. B 13. D 14. B 15. B 16. B 17. D 18. B 19. A 20. E 21. D 22. A 23. B 24. B 25. C 26. D 27. C 28. E 29. D 30. E 31. A 32. A 33. A 34. C 35. D 36. D 37. A 38. A 39. D 40. B 41. E 42. A 43. E 44. B


Grabner, Gail

Grabner, GailB

45. C 46. A 47. C 48. C 49. D 50. A 51. B 52. A 53. C 54. A 55. D 56. A 57. B 58. D 59. A 60. D 61. C 62. C 63. B



Helpful Equations:

degrees K = 273 + C









A) True B) False




Scrambled version C Page 1



A) HPO42- D) PO43-













A. B. C. D.











A) 1 B) 3.5 C) 5 D) 7 E) 9






A) 7.12 B) 6.82 C) 6.52 D) 6.22 E) 7.42





1. B 2. D 3. B 4. D 5. C 6. B 7. D 8. A 9. C 10. A 11. C 12. B 13. B 14. D 15. A 16. D 17. B 18. A 19. E 20. E 21. D 22. B 23. C 24. A 25. C 26. E 27. C 28. A 29. B 30. B 31. C 32. B 33. A 34. B 35. A 36. D 37. D 38. B 39. A 40. B 41. A 42. A 43. A 44. C


Grabner, Gail

Grabner, GailB

45. B 46. C 47. A 48. C 49. D 50. E 51. D 52. A 53. C 54. E 55. D 56. C 57. A 58. C 59. D 60. D 61. B 62. C 63. A


exam1_s14

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d d b b e

kjmol b

c h3po4

c coenzyme

ser b lys c

prime b

kjmol d

c acetic acid