Exam1Fa14

CH 369 Exam 1 September 24, 2014

Name: __________________________________________ eID ________________

Section I (20 points): 1 point each

1. Which of the molecules below contains a phosphodiester group?

A) (a) only D) (b) and (c) B) (b) only E) None of the above C) (c) only

2. In gel filtration the smallest proteins elute first and the largest elute last. A) True B) False

3. What is unique about the nature of a low-barrier H-bond as compared to a typical H-bond? A) The H-bond forms between 2 electronegative elements. B) Only an H nucleus is small enough to approach the lone pair electron cloud. C) The length of the H-bond is shorter and therefore stronger. D) A low-barrier H-bond results in less energy stabilization than in a typical H-bond.

4. A reaction will be spontaneous at all temperatures if what two conditions are met? A) a decrease in enthalpy and decrease in entropy D) an increase in enthalpy and decrease in entropy B) a decrease in enthalpy and increase in entropy E) none of the above C) an increase in enthalpy and increase in entropy

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5. Which of the following is NOT a common component of biomolecules? A) Carbon B) Hydrogen C) Oxygen D) Nitrogen E) Chlorine

6. Which of the following are typical hydrogen bond interactions? A) N!H, H!H, S!H, H!C D) N!H, S!H, H!Si B) N!H, O!H, S!H E) none of the above C) O!H, S!H, C!O

7. Since the peptide bond has partial double bond character, the atoms involved in the peptide bond are nonpolar

A) True B) False

8. -helix or -sheet relates to A) primary structure C) tertiary structure B) secondary structure D) quaternary structure

9. Which of the following would represent the reaction coordinate for a two-step reaction with an initial slow step?

A) A B) B

10. What is the term used to define binding behavior in which the binding of one ligand alters the affinity of binding for a second ligand?

A) cooperativity D) complementary B) stereospecificity E) none are correct C) denaturation

11. What is the conjugate base of the acid, HC2O4-?

A) H2C2O4 B) C2O42- C) HC2O5-

12. Which of the following compounds is amphipathic? A) H2O D) CH3CH2CH2CH2COOH B) CH3CH2CH2CH2CH3 E) Both A and D are correct. C) HOOCCOOH

13. Which of the following is NOT a class of amino acid? A) Nonpolar and neutral D) Basic B) Polar and neutral E) Asymmetric C) Acidic


14. Which of the following amino acids is capable of participating in acid/base catalysis? A) Thr B) Arg C) Met D) Asp E) Gln

15. Enzymes enhance the rates for slow reactions but are not needed for fast reactions. A) True B) False

16. In a micelle or bilayer, the surrounding water is in contact with the more _____ portion of the amphiphilic molecule.

A) oxidized B) reduced C) polar D) nonpolar

17. What are the major types of biological polymers? A) amino acids, nucleotides, sugars D) nucleic acids, proteins and lipids B) proteins, lipids and cholesterol E) none of the above C) proteins, nucleic acids and polysaccharides

18. The heme found in myoglobin is a: A) domain D) peptide B) prosthetic group E) none of the above C) zinc finger

19. The most recently added actin subunits in a microfilament contain bound ADP. A) True B) False

20. F-actin and G-actin refer to the polymeric or monomeric state of actin respectively. A) True B) False

Section II (62 points): 2 points each

21. In the developing fetus, fetal hemoglobin (Hb F) is synthesized beginning at the third month of gestation and continuing until birth. After the baby is born, the concentration of Hb F declines and is replaced with adult hemoglobin (Hb A) as synthesis of the chain declines and synthesis of the chain increases. By the time the baby is six months old, 98% of its hemoglobin is Hb A. In the graph below, which curve represents fetal hemoglobin?

A) A B) B


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

A) 1 B) 3 C) 5 D) 7 E) 9

23. Which of the following biomolecules always contains a building block of one of the other 4 biomolecules? A) Amino acid D) Lipid B) Monosaccharide E) none of the above C) Nucleotide

24. What features/aspects of collagen are important in its structure A) absence of proline D) cross links of cysteine B) left handed helical structure E) none of the above C) low glycine content

25. Which of the following molecules would form a micelle? A) NaCl D) H3PO4 B) CH3COOH E) CH3(CH2)10COO-Na+ C) CH3CH2CH2CH2CH2CH3

26. Which of the tripeptides below has the largest number of polar R groups? A) Tyr-Lys-Met B) Gly-Pro-Arg C) Asp-Ser-Gln D) Asp-His-Pro E) Leu-Gln-Ser

27. H3O+ is the strongest acid that can exist in a biological system. A) True B) False

28. A coupled reaction always involves A) oxidation and reduction. B) esterification. C) reactions that produce energy and reactions that consume energy. D) ATP as a reactant. E) Both B and D must be true.

29. Identify the amino acid below.

A) H B) F C) E D) W E) P


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30. Given the reaction below, tell whether the reactant is being oxidized or reduced.

A) Oxidized B) Reduced

31. How many hydrogen bond acceptor GROUPS are present in the following molecule?

A) 1 B) 2 C) 3 D) 4 E) 5

32. Of the six proteins, actin, myosin, tubulin, kinesin, keratin, and collagen, which contain nucleotide-binding sites?

A) keratin and collagen D) actin, myosin, tubulin, and kinesin B) myosin and kinesin E) none of the above are correct C) actin and tubulin

33. Under certain conditions, peptide bond formation is more thermodynamically favorable than peptide bond hydrolysis. Would you expect chymotrypsin to catalyze peptide bond formation?

A) Yes B) No C) Cannot be determined

34. Which of the following amino acids is affected by oxidation/reduction? A) M B) S C) C D) L E) D

35. Mass spectrometry is highly accurate and can therefore distinguish between the amino acid Ile and Leu. A) True B) False

36. The reaction catalyzed by hexokinase is given below. To which class does the enzyme belong?

A) lyase D) oxidoreductase B) ligase E) hydrolase C) transferase

37. The lysozyme molecule contains regions of helical structure. This statement refers to the _________ structure of the protein.

A) primary B) secondary C) tertiary D) quaternary


38. What is the final pH when 100 mL of 0.5 M HCl is added to 900 mL of water? A) 1.3 D) 0.3 B) 2.3 E) none of the above C) 13.0

39. How would chymotrypsin's catalytic triad be affected by extremely low pH values (assuming that the rest of the protein structure remained intact)?

A) At very low pH values, His would be deprotonated and therefore able to from a hydrogen bond with Ser.

B) At very low pH values, His would be protonated and therefore able to from a hydrogen bond with Ser. C) At very low pH values, His would be deprotonated and therefore unable to from a hydrogen bond

with Ser. D) At very low pH values, His would be protonated and therefore unable to from a hydrogen bond with

Ser.

40. Which of the following could form a covalent bond with acyl groups? A) Asp and Glu B) Lys and Arg C) Cys and Ser D) Tyr E) C and D

41. Which of the following would NOT form a suitable buffer? A) Acetic acid/acetate D) Hydrochloric acid/Chloride B) Carbonic acid/bicarbonate E) Phosphoric acid/dihydrogen phosphate C) Bicarbonate/carbonate

42. When pO2=15 torr, what is the fractional saturation of myoglobin? (p50 = 2.8 torr) A) 0.65 B) 0.58 C) 0.84 D) none are correct

43. The sodium acetate/acetic acid buffer is 0.1 molar in sodium acetate and 0.5 molar in acetic acid. What is the concentration of the buffer?

A) 0.1 molar B) 0.5 molar C) 0.6 molar D) 0.4 molar E) Either A or B depending on whether acid or base is being added to the buffer.

44. A patient suffers from premature zymogen activation, so that the pancreatic enzymes are activated in the pancreas rather than the small intestine -- causing damage to the pancreas. Which of the following would be the most effective in preventing these effects?

A) chymotrypsin inhibitor B) trypsin inhibitor C) elastase inhibitor

45. In a collagen chain, the most common repeating triplet comprises all of the following accept A) glycine D) lysine B) proline E) none of the above C) hydroxyproline


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46. The imidazole side chain of histidine can function as either a general acid catalyst or a general base catalyst because:

A) in the physiological pH range both H+ and OH are present at high concentrations. B) in the physiological pH range, the nitrogen in the ring can be easily protonated/deprotonated. C) one guanidino group is protonated, and the other is deprotonated at physiological pH. D) the imidazole group is a strong reducing agent at physiological pH. E) the sulfur atoms in the ring can either gain or lose a proton at physiological pH.

47. Assuming a temperature of 25oC and an entropy change of +75 J/K/mol, the enthalpy change for a G value of -11.0 kJ/mol is

A) + 15.2 kJ/mol D) - 17.4 kJ/mol B) + 22.5 kJ/mol E) none of the above C) + 11.3 kJ/mol

48. Ser can most likely be conservatively substituted by A) Leu D) Val B) Met E) none of the above C) Thr

49. The height of the activation barrier determines: A) The free energy change of the reaction. B) The rate of the reaction. C) The probability that the reaction will be spontaneous. D) A and C E) A, B and C

50. Protein structure is strongly influenced by A) hydrophilic amino acids that want to be in the core of the protein to stabilize it. B) the hydrophobic effect, that is the protein puts hydrophobic amino acids into the protein core to

shield them from the aqueous environment. C) the presence of multiple loops on the protein surface that bind water and ions to make the protein

more hydrophobic. D) all of the above E) none of the agove

51. The power stroke in muscle contraction is associated with: A) dissociation of ADP from the ATPase D) the binding of ATP to ATPase B) binding of myosin to actin E) none of the above C) the hydrolysis of ATP

Section III (18 points): 3 points each


52. For the reaction in which reactant A is converted to product B, tell whether the process is favorable at (a) 4oC and (b) 37oC, given the information below.

A) Favorable at both (a) and (b) D) Unfavorable at (a) but favorable at (b) B) Unfavorable at both (a) and (b) E) No way to tell C) Favorable at (a) but unfavorable at (b)

53. Lysozyme catalyzes the hydrolysis of a polysaccharide component of bacterial cell walls. The damaged bacteria subsequently lyse (rupture). Part of lysozyme's mechanism is shown below. The enzyme catalyzes cleavage of a bond between two sugar residues (represented by hexagons). Catalysis involves the side chains of Glu 35 and Asp 52. One of the residues has a pK of 4.5; the other has a pK of 5.9. Assign the given pK values to Glu 35 and Asp 52. Would lysozyme be active at pH 8.0?

A) Glu 35 has a pK of 4.5; Asp 52 has a pK of 5.9; Lysozyme would be inactive at pH 8.0. B) Glu 35 has a pK of 4.5; Asp 52 has a pK of 5.9; Lysozyme would be active at pH 8.0. C) Glu 35 has a pK of 5.9; Asp 52 has a pK of 4.5; Lysozyme would be inactive at pH 8.0. D) Glu 35 has a pK of 5.9; Asp 52 has a pK of 4.5; Lysozyme would be active at pH 8.0.

54. Which of the following correctly describes the sequence of events in the myosin-actin cycle? A) myosin release from actin, ATP binds to myosin, myosin binds to another actin subunit, release of Pi

and ADP, stretched myosin returns to original conformation B) myosin release from actin, ATP binds to myosin, myosin binds to another actin subunit, stretched

myosin returns to original conformation, release of Pi and ADP C) ATP binds to myosin, myosin release from actin, myosin binds to another actin subunit, release of Pi

and ADP, stretched myosin returns to original conformation D) ATP binds to myosin, myosin release from actin, myosin binds to another actin subunit, stretched

myosin returns to original conformation, release of Pi and ADP E) myosin release from actin, myosin binds to another actin subunit, ATP binds to myosin, stretched

myosin returns to original conformation, release of Pi and ADP


55. Hemoglobin is 50% saturated with oxygen when pO2 = 26 torr. If hemoglobin exhibited hyperbolic binding (as myoglobin does) with 50% saturation at 26 torr, what would be the fractional saturation when (1) pO2 = 30; and (2) 100 torr? (3)In this case, what would be the effect on the oxygen saturation of Hb in the lungs?

A) (1) 0.54 torr; (2) 0.79 torr; (3) Hb would be less than 100% saturated with O2 B) (1) 0.79 torr; (2) 0.54 torr; (3) Hb would still be 100% saturated with O2 C) (1) 0.54 torr; (2) 0.79 torr; (3) Hb would still be 100% saturated with O2 D) (1) 0.46 torr; (2) 0.21 torr; (3) Hb would still be 100% saturated with O2 E) (1) 0.54 torr; (2) 7.9 torr; (3) Hb would still be 100% saturated with O2

56. What amount of 0.1 M NaH2PO4 and 0.1 M Na2HPO4 would be required to make 0.5 L of 0.1 M, pH 7.2 phosphate buffer (pK 6.82)?

A) 418 mL 0.1 M NaH2PO4 and 82 mL 0.1 M Na2HPO4 B) 150 mL 0.1 M Na2HPO4 and 350 mL 0.1 M NaH2PO4 C) 400 mL 0.1 M NaH2PO4 and 100 mL 0.1 M Na2HPO4 D) 100 mL 0.1 M NaH2PO4 and 400 mL 0.1 M Na2HPO4 E) 353 mL 0.1 M Na2HPO4 and 147 mL 0.1 M NaH2PO4

57. You have a mixture of 3 proteins, listed in the table below with their relevant properties. You are interested in isolating aspartate transaminase using ion exchange chromatography with DEAE resin. Given the values in the table below: 1) what pH would you use in order to ensure that aspartate transaminase protein binds to the column and that the others do not? Assume that your efforts are successful -- 2) how will you elute aspartate transaminase from the column? Choose the correct conditions from the list below.

Protein pIAspartate transcarbamylase 9.8Myoglobin 7.0Aspartate transaminase 5.0

A) 1) Initial pH = 10.0; 2) lower pH to 6 D) 1) Initial pH = 6; 2) lower pH to 5 or less B) 1) Initial pH = 8; 2) raise pH to 10 E) 1) Initial pH = 8; 2) lower pH to 7 C) 1) Initial pH = 4; 2) raise pH to 5 or higher


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Answer Key - Exam1Fa14

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


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45. D 46. B 47. C 48. C 49. B 50. B 51. A 52. D 53. C 54. C 55. A 56. E 57. D



Name: __________________________________________ eID ________________








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A) A B) B










A) H2C2O4 B) C2O42- C) HC2O5-


A) True B) False












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Ser.








A) 1 B) 2 C) 3 D) 4 E) 5







A) A B) B



A) 1 B) 3 C) 5 D) 7 E) 9










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


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45. A 46. B 47. B 48. B 49. C 50. B 51. C 52. C 53. C 54. D 55. D 56. E 57. A


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A) A B) B





A) True B) False









A) H2C2O4 B) C2O42- C) HC2O5-







A) 1 B) 2 C) 3 D) 4 E) 5


A) 1 B) 3 C) 5 D) 7 E) 9





A) A B) B






Ser.















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


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45. C 46. B 47. C 48. C 49. D 50. C 51. C 52. C 53. D 54. E 55. C 56. A 57. D


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