Haemoglobin is an oxygen carrying molecule found in red blood cells. Haemoglobin is made up of four polpeptide chains (2 alpha, 2 beta), and consists of four haem groups (iron associated with heam) containing a central iron molecule. This iron molecule is responsible for binding to oxygen to transport it around the body (carrying up to four oxygen molecules). Oxygen binds to haemoblobin because it is not very soluble in blood, therefore, to meet the body's demands for oxygen, haemoglobin must carry oxygen. Haemoglobin is thus a carrier molecule. Haemoglobin not only has a role in delivering oxygen, but a role in removing carbon dioxide from metabolising tissues. Therefore, through removing the carbon dioxide it allows the process of respiration to occur, by providing oxygen to form energy necessary for the body's every function, whilst removing the waste product (carbon dioxide).
Haemoglobin's structure is related to it's function. Every oxygen molecule that binds causes a conformational change to the overall molecule, making the haemoglobin more likely to bind to another oxygen molecule. This process ensures maximum efficiency in loading and unloading oxygen where necessary (eg. picking up vast amounts of oxygen in the lungs yet unloading huge amounts to metabolising tissue.) To conclude, haemoglobin has a vital role in the carraige of oxygen and therefore respiration and metabolism.
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