PRACTICE EXAM 1 BC 351 Amino Acid gly ser glu asp lys arg his val pro pK1 COOH 2 34 2 21 2 19 1 88 2 18 2 17 1 82 2 32 1 99 pK2 amino 9 60 9 15 9 67 9 60 8 95 9 04 9 17 9 62 10 96 pKR side chain 13 6 4 25 3 65 10 53 12 48 6 00 Matching Instructions Fill in the correct bubble for the BEST answer to each of the following There is only one correct answer per question Set One Question 1 4 on your answer sheet 1 Hydrogen bond 2 Ionic bond 3 pKa 4 Ka 5 Equilibrium A A bond whose dissociation energy is inversely related to the polarity of the solvent as measured by the dielectric constant B If this value is small then the molecule whose ionization equilibrium it describes is considered a base C If this value is large then the molecule whose ionization equilibrium it describes is considered a base D A bond that forms between two partial charges E The rate of the forward reaction matches the rate of the backward reaction Set Two Question 5 8 on your answer sheet 6 Levinthal s paradox 7 Anfinsen s experiment 8 N terminus 9 C terminus 10 Subunit A The only amino acid in a protein with a free carboxyl group B The only amino acid in a protein with a free amino group C Demonstrated that the pre determined path necessary for a protein to fold is determined by the primary structure of the protein D Demonstrated that folding must occur via a predetermined path E A protein structural feature not found in ribonuclease Multiple choice Instructions Fill in the correct bubble for the BEST answer to each of the following There is only one correct answer per question 11 Water evaporation occurs spontaneously and is endothermic Based upon this statement which of the following is true A The change in enthalpy for this reaction has a negative value and this is related to the fact that water in the vapor phase participates in less hydrogen bonds than in the liquid phase B The change in enthalpy for this reaction has a positive value and this is related to the fact that water in the vapor phase participates in more hydrogen bonds than in the liquid phase C The change in entropy must be positive meaning that order has increased D The change in entropy must be positive meaning that order has decreased E The change in entropy must be negative meaning that order has decreased 12 The bond dissociation energy for an ionic bond in sodium chloride A increases when sodium chloride is transferred from a polar to a non polar solution due to an increase in the distance between the two ions Na and Cl B decreases when sodium chloride is transferred from a polar to a non polar solution due to an increase in the distance between the two ions Na and Cl C increases when sodium chloride is transferred from a polar to a non polar solution due to solvent effects D decreases when sodium chloride is transferred from a polar to a non polar solution due to solvent effects E None of the above are correct and therefore E is my best choice 13 According to Coulomb s law F Q1Q2 r2 ion ion interactions A are stronger in the hydrophobic core as compared to the same bond on the exterior of a protein making the S negative B are stronger in the hydrophobic core as compared to the same bond on the exterior of a protein making the S positive C are stronger in the hydrophobic core as compared to the same bond on the exterior of a protein and will not effect the value of S but will cause H to be positive D are weaker in the hydrophobic core as compared to the same bond on the exterior of a protein and will not effect the value of S but will cause H to be positive E None of the above statements are true 14 The predominant form of glutamic acid glutamate at pH 8 A will have a deprotonated side chain and 1 charge for this group the side chain B will have a side chain capable of forming an ionic bond with the side chain of aspartic acid aspartate at the same pH C will have a net charge of 2 D will have a side chain that will repel the side chain of lysine at the same pH E All of the above are correct statements 15 The amino acid show to the right is A B C D E Tyr Ser Thr Asp Asn 16 Based on the following graph which statement is correct A The graph represents the titration of an amino acid that falls in the positively charge R group category B The charge on the amino acid side chain at pH 6 is 1 C The charge on the amino acid at pH 6 is 2 D The amino acid is Asp E None of the above 17 The figure below is that of a bond between two amino acids which of the following statements is true A Rotation around the C N bond is restricted due to its partial double bond character B The C N bond is free to rotate and its torsion angle is referred to as the phi angle which in a protein is unrestricted in the number of angles it can adopt C The C C bond is free to rotate and its torsion angle is referred to as the psi angle which in a protein is unrestricted in the number of angles it can adopt D All of the above 18 Experiments on denaturation and renaturation of the enzyme ribonuclease RNase in combination with the thought experiment performed by Levinthal have shown that A folding of denatured RNase into the native active conformation requires the input of energy and favors the folded native state B that folding is a random sampling of all the possible conformations a protein could adopt C the primary sequence of RNase is sufficient amount of information to determine the proteins specific secondary and tertiary structure D proteins that exhibit disulfide bonds will fold spontaneously but those without require the input of energy E None of the above 19 An helix would be destabilized most by A B C D E interactions b w Asp and Arg residues 3 amino acids apart the introduction of a Pro residue into the middle of a helix interactions between two adjacent 3 4 away from each other hydrophobic Leu residues interactions b w Lys and Glu residues 3 amino acids apart two Lys residues in a row in the primary structure 20 Which of the following statements is true A The total change in enthalpy H for a protein folding event must be negative because so many new electrostatic interactions form in the newly folded protein B The total change in enthalpy H for a protein folding event can be negative if the protein …