Which of the following mechanisms explains how carbon dioxide affects O₂ binding to Hb?
A)by directly binding to heme-Fe in the oxygen binding site
B)by forming iron carbonate with the heme-iron
C)by forming HCO₃-,which combines with H⁺ to increase CO₂ binding
D)by forming H⁺ + HCO₃-,where the H⁺ is an antagonist to oxygen binding to Hb

Question

Quizplus · Accepted Answer

Carbon dioxide forms carbonic acid (H₂CO₃) in the blood, which dissociates into bicarbonate (HCO₃-) and hydrogen ions (H⁺). The increase in H⁺ concentration lowers the blood pH, which in turn affects the oxygen-binding affinity of hemoglobin (Hb) through the Bohr effect. The Bohr effect describes how a decrease in pH (increase in H⁺ concentration) reduces hemoglobin's affinity for oxygen, facilitating oxygen release to tissues. This mechanism does not involve CO₂ directly binding to the heme-iron or forming iron carbonate; instead, it operates through the changes in pH mediated by the products of CO₂ hydration.

Which of the Following Mechanisms Explains How Carbon Dioxide Affects