Protein:

It is formed of carbon, hydrogen, oxygen, nitrogen, and usually sulfur. Nitrogen is a basic element found in the protein. It consists of amino acids which are monomers of proteins. Each amino acid consists of at least one amino group and one carbonyl group. There are 20 kinds of amino acids divided into two groups. The non-essential amino acids are those that are synthesized inside the body and need not 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 proteins don’t consist of the same type of amino acid. The first class of complete proteins is those which contain almost all types of essential amino acids. Such as meat, soybeans, etc. The nonessential or incomplete proteins are those that contain relatively less no. of essential amino acids such as plant proteins.

Sources: Meat, fish, egg, milk, pulses, soybean, 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 infants, children, pregnant and lactating women, etc. Our bodies have no mechanism to store the protein. Excess proteins are converted into urea and expelled through urine.

Function:

i) It is the 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 proteins help in the contraction of muscles.

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

iii) It is an essential component of the cell.

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

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

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