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Q.
How many $O _{2}$ molecules can bind with single molecule of $Hb$ ?
Breathing and Exchange of Gases
Solution:
Haemoglobin consists of four polypeptide chain $(2 \alpha$ and $2 \beta)$ having heme as prosthetic group. Heme is iron $\left( Fe ^{2+}\right)$ containing prophyrin ring. One haemoglobin binds four oxygen molecules, one per heme and form oxyhemoglobin.
$Hb +4 O _{2} \rightleftharpoons Hb \left( O _{2}\right)_{4}$