HEMOGLOBIN SYNTHESIS, FUNCTION, CATABOLISM AND EXCREATION
We know well that the main function of the red blood cell is to carry oxygen to the tissues and return carbon dioxide to the lungs. This process of gaseous exchange is achieved by the specialized protein in the red blood cell, hemoglobin. Each red blood cell then contains approximately 640 million hemoglobin molecules. Hemoglobin is an oxygen-binding protein that is mainly found in erythrocytes that aids in transporting oxygen from the lungs to the tissues. The hemoglobins have a molecular weight of about 68,000 and compromises almost one third of the weight of a red blood cell. Each hemoglobin molecule is a tetramer made of four polypeptide globin chains. A heme moiety made up of an organic protoporphyrin ring and a central iron ion in the ferrous state(Fe2+) is found in each globin subunit. Each heme moiety contains an iron molecule that is able to bind and unbind oxygen, enabling the organism to transport oxygen. The most common type of hemoglobin in the adult is HbA, which c