Haemoglobin is iron containing compund that binds to oxygen gas. It is found in the red blood cells of vertebrates. It transports oxygen from the respiratory organ, the lungs, to the different cells of body. It is a protein that contains a quanternary structure made up of 4 sub-units. They consist of 2 alpha sub units and 2 beta subunits. Each subunit conatins a haeme group which contains and iron atom. Each iron atom binds to 1 oxygen molecule. Thus 1 haemogobin molecule transports 8 atoms of oxygen. When absorbtion of oxygen occurs haemoglobin becomes oxyhaemoglobin and it forms the reddish colour of the red blood cells. Upon arrival at a cell it deposits its oxygen thus allowing oxidization of glucose to take place via respiration. This releases energy in form of ATP. The waste product, carbon dioxide is transported by haemoglobin to the lungs for expiration.
Berg, J. Stryer, L. Tymoczko J. (2012) Biochemistry, 7th Edition : W.H. Freeman and Company. Chapter 7, Page 203-207