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Allosteric Effects (Biochemistry) Question and Answers-Page first

Allosteric Effects problems


  • 1. The Hill coefficient (nH) for myoglobin and hemoglobin are respectively

  • Options
  • A. 2.8 and 1.0
  • B. 1.0 and 2.8
  • C. 1.2 and 4.5
  • D. 4.5 and 1.2
  • Discuss
  • 2. An allosteric activator

  • Options
  • A. increases the binding affinity
  • B. decreases the binding affinity
  • C. stabilizes the R state of the protein
  • D. both (a) and (c)
  • Discuss
  • 3. The conformational changes from the T to the R state is initiated by

  • Options
  • A. binding of oxygen to the heme
  • B. movement of the proximal histidine towards the heme
  • C. movement of the F-helix, which contains the proximal His
  • D. reorganization of protein-protein contacts between the individual subunits
  • Discuss
  • 4. When protein binds two ligands in a non-cooperative manner, then the x-intercept of the Scatchard Plot is

  • Options
  • A. 1
  • B. 2
  • C. not defined
  • D. none of the above
  • Discuss
  • 5. The specificity of a ligand binding site on a protein is based on

  • Options
  • A. the absence of competing ligands
  • B. the amino acid residues lining the binding site
  • C. the presence of hydrating water molecules
  • D. the opposite chirality of the binding ligand
  • Discuss
  • 6. A protein that binds two ligands in a non-cooperative manner will show

  • Options
  • A. a sigmodial binding curve
  • B. a hyperbolic binding curve
  • C. a linear Scatchard Plot
  • D. both (b) and (c)
  • Discuss
  • 7. O2 binding to hemoglobin results in

  • Options
  • A. 100-fold higher affinity for the last O2 bound than for the first
  • B. extensive protein conformational change
  • C. both (a) and (b)
  • D. 100-fold lower affinity for the last O2 bound than for the first
  • Discuss
  • 8. In hemoglobin, allosteric effects occur

  • Options
  • A. only in humans
  • B. for maintaining Fe in the Fe2+ state
  • C. to minimize oxygen delivery to the tissues
  • D. to maximize oxygen delivery to the tissues
  • Discuss
  • 9. Bisphosphoglycerate (BPG) cannot bind to the oxygenated R state of hemoglobin because

  • Options
  • A. it is displaced from the heme by oxygen
  • B. it is displaced from the heme by movement of the proximal histidine
  • C. its binding pocket becomes too small to accommodate BPG
  • D. BPG binds to the R state with the same affinity as the T state
  • Discuss
  • 10. Small molecules affect hemoglobin (Hb) by

  • Options
  • A. decreasing Hb affinity for O2
  • B. increasing [H+]
  • C. increasing Hb affinity for O2
  • D. increasing [H+] and decreasing Hb affinity for O2
  • Discuss

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