Homework answers / question archive / Gateway Technical College BIO 806-177 Lecture 7 : Myoglobin and Hemoglobin: 1)Which of the following statements about the differences between myoglobin and hemoglobin is FALSE? Hemoglobin consists of 4 subunits while myoglobin has one At PO2 = 30mg Hg, myoglobin binds oxygen at higher affinity than does hemoglobin Myoglobin has a sigmoidal oxygen binding curve, while hemoglobin has a hyperbolic binding curve Myoglobin binds one heme molecule, while hemoglobin binds four Which of the following statements about the heme binding sites of hemoglobin is TRUE? Upon binding to oxygen, the heme group becomes planar Each heme iron is coordinated by two histidine sidechains Upon binding to oxygen, two histidine sidechains coordinate the O2 molecule All of the above are true Which of the following statements about the allostery of hemoglobin is TRUE? The cooperativity of oxygen binding is largely due to heme-heme interactions between subunits Conformational changes between the R and T state are not believed to contribute to the cooperativity of oxygen binding Cooperativity in oxygen binding gives rise to the sigmoidal oxygen binding curve ALL of the above are true Which of the following statements about the interaction of BPG and hemoglobin is TRUE? Oxygen delivery is enhanced at high altitudes by strengthening hemoglobin’s affinity to oxygen Oxygen delivery is enhanced at high altitudes by weakening hemoglobin’s affinity to oxygen BPG does not weaken or strengthen hemoglobin’s affinity to oxygen but modulates the cooperativity of binding BPG does not weaken or strengthen hemoglobin’s affinity to oxygen but competes with hemoglobin for O2 Which of the following mutations would you expect to be MOST detrimental to hemoglobin’s affinity to bind oxygen? (alpha) F8 His ? Leu (beta) A3 Glu ? Val (alpha) HC3 Arg ? His ALL of the above have the same effect on hemoglobin binding to O2 Which of the following statements about the Bohr effect is FALSE? The pH responsiveness is due to protonation of a histidine residue It increases the hemoglobin’s ability to deliver oxygen in hypoxic conditions At high pH, hemoglobin has a hyperbolic binding curve ALL of the above are TRUE Which of the following statements about sickle-cell hemoglobin is TRUE? It dramatically weakens the binding of hemoglobin to oxygen It leads to oxidation of heme to Fe(3+) It reduces the pH-induced binding affinity changes of hemoglobin to oxygen It involves a mutation far from the site of oxygen binding Which of the following statements about the symmetry model of allosteric change in hemoglobin is TRUE? Binding of oxygen at one subunit increases oxygen affinity at neighboring subunits Under this model, it is not possible to have a tetramer contain both R and T subunits The model describes cooperativity of hemoglobin binding as largely a change in dynamics rather than in conformation ALL of the above are true        

Gateway Technical College BIO 806-177 Lecture 7 : Myoglobin and Hemoglobin: 1)Which of the following statements about the differences between myoglobin and hemoglobin is FALSE? Hemoglobin consists of 4 subunits while myoglobin has one At PO2 = 30mg Hg, myoglobin binds oxygen at higher affinity than does hemoglobin Myoglobin has a sigmoidal oxygen binding curve, while hemoglobin has a hyperbolic binding curve Myoglobin binds one heme molecule, while hemoglobin binds four Which of the following statements about the heme binding sites of hemoglobin is TRUE? Upon binding to oxygen, the heme group becomes planar Each heme iron is coordinated by two histidine sidechains Upon binding to oxygen, two histidine sidechains coordinate the O2 molecule All of the above are true Which of the following statements about the allostery of hemoglobin is TRUE? The cooperativity of oxygen binding is largely due to heme-heme interactions between subunits Conformational changes between the R and T state are not believed to contribute to the cooperativity of oxygen binding Cooperativity in oxygen binding gives rise to the sigmoidal oxygen binding curve ALL of the above are true Which of the following statements about the interaction of BPG and hemoglobin is TRUE? Oxygen delivery is enhanced at high altitudes by strengthening hemoglobin’s affinity to oxygen Oxygen delivery is enhanced at high altitudes by weakening hemoglobin’s affinity to oxygen BPG does not weaken or strengthen hemoglobin’s affinity to oxygen but modulates the cooperativity of binding BPG does not weaken or strengthen hemoglobin’s affinity to oxygen but competes with hemoglobin for O2 Which of the following mutations would you expect to be MOST detrimental to hemoglobin’s affinity to bind oxygen? (alpha) F8 His ? Leu (beta) A3 Glu ? Val (alpha) HC3 Arg ? His ALL of the above have the same effect on hemoglobin binding to O2 Which of the following statements about the Bohr effect is FALSE? The pH responsiveness is due to protonation of a histidine residue It increases the hemoglobin’s ability to deliver oxygen in hypoxic conditions At high pH, hemoglobin has a hyperbolic binding curve ALL of the above are TRUE Which of the following statements about sickle-cell hemoglobin is TRUE? It dramatically weakens the binding of hemoglobin to oxygen It leads to oxidation of heme to Fe(3+) It reduces the pH-induced binding affinity changes of hemoglobin to oxygen It involves a mutation far from the site of oxygen binding Which of the following statements about the symmetry model of allosteric change in hemoglobin is TRUE? Binding of oxygen at one subunit increases oxygen affinity at neighboring subunits Under this model, it is not possible to have a tetramer contain both R and T subunits The model describes cooperativity of hemoglobin binding as largely a change in dynamics rather than in conformation ALL of the above are true        

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