1. The four subunits of hemoglobin exhibit cooperative binding. As pO2 of blood changes entering the pulmonary veins, the KM of hemoglobin towards this substrate:
When blood reaches your tissues, the sigmoidal curve shifts to the right to allow oxygen to diffuse into cells. This means the KM was increased (less affinity for oxygen). Once blood reaches your lungs (and pO2 increases), you expect a left shift in the sigmoidal curve, thus KM was decreased from its previous value (higher O2 affinity). So wouldn't the answer be B.
- (A) Increases
- (B) Decreases
- (C) Remains Unchanged
- (D) Could be higher or lower, depending on the saturation
When blood reaches your tissues, the sigmoidal curve shifts to the right to allow oxygen to diffuse into cells. This means the KM was increased (less affinity for oxygen). Once blood reaches your lungs (and pO2 increases), you expect a left shift in the sigmoidal curve, thus KM was decreased from its previous value (higher O2 affinity). So wouldn't the answer be B.