Feedback for Multiple Choice Quiz 13

  1. The correct answer is a very important definition. Binding can be and is described as association or equivalently, dissociation.

  2. Myoglobin binds O2 noncooperatively (nH = 1). Hemoglobin binds O2 cooperatively (nH > 1, but always less than the number of interacting subunits).

  3. The whole rationale of hemoglobin cooperativity is to allow it to load O2 efficiently in the lungs and to unload the O2 in the peripheral tissues.

  4. Lower pH decreases O2 affinity (Bohr Effect) enabling blood to deliver more O2 to exercising muscle. The converse of the incorrect answers are true.

  5. The conformational change is the structural basis of hemoglobin cooperativity. It causes a lower initial affinity for O2, but a higher final affinity.

  6. The slope of the Hill plot is nH. See question 2. The second is a characteristic of all real Hill Plots, i.e. the nH value corresponds to the slope at half saturation; on either side, the slope approaches a value of 1.0.
  All of the correct answers have a green check mark.
  Incorrect answers have the "red-lit" button next to your choice.