Hemoglobin F

Question

Hemoglobin F

Quizplus · Accepted Answer

Hemoglobin F (fetal hemoglobin) contains two alpha and two gamma chains, whereas hemoglobin A (adult hemoglobin) contains two alpha and two beta chains. Hemoglobin F has a higher affinity for oxygen than hemoglobin A, enabling the developing fetus to extract oxygen more efficiently from maternal blood. Hemoglobin F also binds less 2,3-DPG (diphosphoglycerate) than hemoglobin A, which shifts the oxygen dissociation curve to the left, further enhancing oxygen extraction by fetal tissues. Hemoglobin F is decreased after birth and replaced by higher levels of hemoglobin A, which is the predominant hemoglobin in adults. Sickle-cell anemia is caused by a mutation in the beta chain of hemoglobin, not the gamma chain that is found in Hemoglobin F. Therefore, choice D is incorrect.