Chapter 7 Hemoglobin:A Portrait of a Protein in Action 7 36.Which is not correct concerning the models that are accepted to describe cooperative binding? A)In the sequential model,the binding of a ligand changes the conformation of the subunit to which it binds,which in turn induces a change in neighboring subunits. B) All known allosteric proteins exhibit either the concerted or sequential model exclusive of the other. C) Both models incorporate a low affinity T-state and a higher affinity R-state D) Both models explain the sigmoid-shaped binding curve. E)In the concerted model,all molecules exist either in the T-state or the R-state Ans:B Section:7.2 37.Consider the oxygen-binding profile at three different pH values of 7.6,7.4,and 7.2.Which statement is most correct? Hb Oxygen binding 0.8 0.6 0.4 Z 0.2 0 20 40 60 80 100 120 p02(torr) A) Curve X most likely corresponds to pH 7.2 B) Curve Z most likely corresponds to pH 7.6. C) Hb has a higher affinity for oxygen at the pH of curve Z. D) Curve Y most likely corresponds to pH 7.4. E)pH has no effect on the oxygenation of hemoglobin. Ans:D Section:7.3 38.What would be the expected result of a Lys residue being substituted with a Ser residue in the BPG binding site of hemoglobin? A)BPG would bind tighter because of the loss of a positive charge B) BPG would bind tighter because of the gain of a positive charge. C) BPG would bind less tightly because of the loss of a positive charge D) BPG would bind less tightly because of the gain of a positive charge. E)This substitution would have no effect on the binding of BPG Ans:C Section:7.3Chapter 7 Hemoglobin: A Portrait of a Protein in Action 7 36. Which is not correct concerning the models that are accepted to describe cooperative binding? A) In the sequential model, the binding of a ligand changes the conformation of the subunit to which it binds, which in turn induces a change in neighboring subunits. B) All known allosteric proteins exhibit either the concerted or sequential model exclusive of the other. C) Both models incorporate a low affinity T-state and a higher affinity R-state. D) Both models explain the sigmoid-shaped binding curve. E) In the concerted model, all molecules exist either in the T-state or the R-state. Ans: B Section: 7.2 37. Consider the oxygen-binding profile at three different pH values of 7.6, 7.4, and 7.2. Which statement is most correct? A) Curve X most likely corresponds to pH 7.2. B) Curve Z most likely corresponds to pH 7.6. C) Hb has a higher affinity for oxygen at the pH of curve Z. D) Curve Y most likely corresponds to pH 7.4. E) pH has no effect on the oxygenation of hemoglobin. Ans: D Section: 7.3 38. What would be the expected result of a Lys residue being substituted with a Ser residue in the BPG binding site of hemoglobin? A) BPG would bind tighter because of the loss of a positive charge. B) BPG would bind tighter because of the gain of a positive charge. C) BPG would bind less tightly because of the loss of a positive charge D) BPG would bind less tightly because of the gain of a positive charge. E) This substitution would have no effect on the binding of BPG. Ans: C Section: 7.3