Protein:

It is formed of carbon, hydrogen, oxygen, nitrogen, and usually sulphur. The nitrogen is basic element found in the protein. It consists amino acids which are monomers of  proteins. Each amino acid consists at least one amino group and one carbonyl group. There are 20 kinds of amino acids divided in two groups. The non-essential amino acids are those which are synthesized inside the body and need not to be present in our diet. These are 12 in number.  The essential amino acid are those, which are not present in our diet. These are 8 in number. All protein don’t consists same type of amino acid. The first class of or complete proteins are those which contains almost all type of essential amino acids. Such as meat, soyabean, etc. The non essential or incomplete protein are those which contains relatively less no. of essential amino acids such as plant proteins.

Sources: Meat, fish, egg, milk,pulses, soyabean, green vegetables, etc.

Daily requirement:

 A  normal adult person should intake about 100 gm of protein per day. About 205 of our diet must contain protein. This requirement become more for infant, children, pregnant  and lactating women etc. Our body have no any mechanism to store the protein. Excess proteins are converted into urea and expelled out through urine.

Function:

i) It is essential building block of the body. In the form of ossein, it forms bone, in the form of chondrin it forms the cartilage.

ii) The actin and myosin protein help in contraction of muscles.

ii) Some protein like hormones and enzymes regulates the metabolic activities of the body.

iii) It is essential component of the cell.

iv) In the form of Haemoglobin, it helps in transport of respiratory gases.

v) It causes the formation of connective tissue, ligaments, tendon, etc.

vi) In the form of fibrinogen, it helps in clotting of blood.