Question

Identify the polypeptide subunits present in the adult haemoglobin.

• A. Two $\alpha$-and two $\beta$-subunits
• B. Four $\alpha$-subunits
• C. Four $\beta$-subunits
• D. Three $\alpha$-subunits and one $\beta$-subunits

Answer 1

The correct option is A Two $\alpha$-and two $\beta$-subunits

Haemoglobin is a respiratory pigment present in the RBC of the blood. It is a oligoprotein which has four polypeptide chain, two alpha chain and two beta chain. It has a quaternary structure where each polypeptide has heme group with iron in the center. The polypeptide are linked together by the disulphide groups. The structure is stabilized by h-bonds. It is a chromoprotein because it has heme as a cofactor, which is iron containing pigment and makes the blood appear red. Each iron combines with a oxygen molecule.

So, the correct answer is option A.