Hemoglobin  is the iron-containing oxygen-transport metalloprotein in red blood cells.  Hemoglobin in the blood carries oxygen from the lungs to the rest of the body  where it releases the oxygen to burn nutrients to provide energy to power the functions of the organism, and collects the resultant carbon dioxide to bring it back to the lungs to be exhaled. (adapted from wikipedia)


Hemoglobin makes up about 97% of the red blood cells’ dry content, and around 35% of the total content (including water). Hemoglobin has an oxygen binding capacity of 1.34 ml O2 per gram of hemoglobin which increases the total blood oxygen capacity seventy-fold compared to dissolved oxygen in blood.  The hemoglobin molecule can bind (carry) up to four oxygen molecules.

Hemoglobin tetramers are comprised of the four subunits, two α-globin chains and two β-globin chains all of which take the form of alpha helices

Additional image (artist representation) here

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