Why Iron is required as a part of haemoglobin?

As a part of haemoglobin, iron is required for the transport of oxygen, to all cells in the body. Thus, haemoglobin is critical for cell respiration. Most of the iron in the body is present in the erythrocytes as haemoglobin, a molecule composed of four units, each containing one haem group and one protein chain. The structure of haemoglobin allows it to be fully loaded with oxygen in the lungs and partially unloaded in the tissues (e.g. in the muscles), the iron-containing oxygen storage protein in the muscles, myoglobin, is similar in structure to haemoglobin but has only one haem unit and one globin chain. As myoglobin, iron functions as a ready source of oxygen to the muscles. Iron is thus crucial for the survival, growth and normal functioning of the human system. Let us now read about the consequences of deficiency and iron overload in the body.