The Function Of Haemoglobin And Oxygen

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Haemoglobin is a protein molecule in the red blood cell rich in iron. The major function of haemoglobin is to transport oxygen (O2) from the lungs. The haemoglobin and oxygen combination is called oxyhaemoglobin, Haemoglobin that has released oxygen is called reduced haemoglobin or deoxyhaemoglobin which has a high affinity for co2 (Marieb, 2014).for this reason oxygen is bind to the oxyhaemoglobin in the lungs and carried through the blood stream to the tissues. Oxygen is then released to myoglobin (a red protein containing haem that carries and stores oxygen in muscle cells) which is further transported in to the mitochondria be used for aerobic respiration, in exchange the deoxyhemoglobin picks up 2 protons and 2 molecules and returns to the lungs where it is released through exhalation. (McDowall, 2005)
Structure of haemoglobin is composed of four polypeptides, two identical chains called the alpha -polypeptide chains consisting of 141 amino acids each and beta-polypeptide chains containing 146 amino acids each. Alpha and Beta each contain 8 helical segments. There are four globin chains each composed of four heme groups attached to each of the four histidines. that combines with four molecules of oxygen (see figure 1). When an iron atom is bonded to oxygen, haemoglobin changes colour from purplish pink to bright red (oxyhaemoglobin) and when deoxygenate is changes to blue. (Toole, 2004)
Haemoglobin is essential for the human body because

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