Question

If four molecules of oxygen bind to haemoglobin then the compound oxyhaemoglobin formed can be represented as

• A. $Hb{O}_2$
• B. $Hb{O}_6$
• C. $Hb{O}_4$
• D. $Hb{O}_8$

Answer 1

The correct option is D $Hb{O}_8$

RBC is a red blood cell which contains haemoglobin iron containing pigment. Each heme group contains iron pigments in it. Iron helps in the binding of gases with RBC.
Oxygen binding to hemoglobin is expressed as a percentage.
1 hemoglobin+1 $O_2$ molecule = hemoglobin is 25% saturated
1 hemoglobin+2 $O_2$ molecule = hemoglobin is 50% saturated.
1 hemoglobin+3 $O_2$ molecule = hemoglobin is 75% saturated.
1 hemoglobin+4 $O_2$ molecule = hemoglobin is 100% saturated.
$\underset{\underset{\text{(uncombined or deoxygenate hemoglobin)}}{\text{Reduced hemoglobin}}}{\text{Hb}}+O_2\rightleftharpoons \underset{\underset{\left(\text{combined or oxygenated hemoglobin}\right)}{\text{Oxyhemoglobin}}}{Hb{O}_2}$
Fig. When a single heme binds to $O_2$ then it is represented as $Hb{O}_2$, and when two $O_2$ binds it is represented as $Hb{O}_4$, and so on. So when four $O_2$ binds it is represented as $Hb{O}_8$.