Question

Research proteins -- choose a protein and research its function, general structure, and describe its primary role in the human body.

Answer 1

Ans. Let us choose the protein 'Hemoglobin' and understand its structure,functions and primary role in the human body.

Structure: Hemoglobin is a protein present in the red blood cells,made up of four polypeptide chains;two alpha chain containing 141 amino acid residues each and two beta chains containing 146 amino acid residues each,held together by non-covalent bond.Although the two chains have different sequences of amino acids,they fold up to form a similar 3-D structure.Each of the chain contains a compound called heme,which contains iron and hence there are four oxygen binding sites on the hemoglobin molecules.It is the presence of this heme group that helps the hemoglobin in the transportation of oxygen in the bloodstream.

Functions: Following are the various functions of Hemoglobin:

• It is a carrier of both oxygen and carbon dioxide in the body.
• It gives the blood its red color.
• It helps the red blood cells in maintaining its shape.
• It acts as a buffer by maintaining the blood's pH at 7.4.
• It helps in transportation of drugs to their site of action.

Primary role of Hemoglobin in the human body:The primary role of hemoglobin is the transportation of oxygen from the lungs to all other parts of the body.The oxygen binding capacity of hemoglobin is primarily due to the presence of the compound known as heme which has affinity for oxygen.When oxygen bounds to hemoglobin,it is referred to as oxyhemoglobin.Whenever blood reaches a tissue that is oxygen deficient,the oxygen gets dissociated from hemoglobin and is diffused into the tissue.Another important role of hemoglobin is to transport carbon dioxide from the tissues to lungs.The hemoglobin bound to carbon dioxide is referred to as carbaminohemoglobin.About 80 percent of the carbon dioxide is transported via plasma fluid.