Studies of oxygen transport in pregnant mammals show that the O2-saturation curves of fetal and maternal blood are mark- edly different when measured under the same conditions. Fetal erythrocytes contain a structural variant of hemoglobin, HbF, consisting of two α and two γ subunits ( α2γ2), whereas maternal erythrocytes contain HbA ( α2β2). a. Which hemoglobin has a higher affinity for oxygen under physiological conditions, HbA or HbF?
b. What is the effect of BPG on the O2 affinity of hemoglobin?