Haemoglobin molecule - stock illustration

Haemoglobin, molecular model. Haemoglobin is a metalloprotein that transports oxygen around the body in red blood cells. Each molecule consists of iron-containing haem groups (sticks) and globin proteins (amino acid chains, coils). Each globin protein is wrapped around a haem group, protecting it from being oxidised and destroyed by the oxygen it is intended to transport. The iron within each haem group reversibly bonds to oxygen and carbon dioxide in the blood.