Proteins are nitrogenous compounds being made up of carbon, hydrogen, oxygen and nitrogen. Proteins also contain sulphur. In living systems proteins play an important role in the structural organisation eg., cell membrane, hairs, nails and muscles. Many of the proteins serve as enzymes. They are named as functional proteins.
The building blocks of proteins are aminoacids. There are approximately twenty different types of amino acids, such as glycine, alanine, serine, valine, leucin, proline etc. The amino acids are classified as essential and non essential amino acids. Essential amino acids can not be synthesised in our body. Hence they should be made available through food. The essential amino acids are arginine, valine, histidine, isoleucine, leucine, lycine, methionine, phenylalanine, threonine and tryptophan. The non-essential amino acids can be synthesized in our body from other compounds. Such amino acids need not be added in the diet.
A protein (or) a polypetide chain is formed of several amino acids linked with each other by peptide bonds. This linear arrangement is termed as primary organisation of a protein. However in most of the proteins, the straight chain structure gets complicated, into secondary, tertiary or quaternary stages. These levels are due to several other chemical bonds. The complicated nature of a particular protein is specifically required for its prescribed function. The amino-acids sequence and level of ogranisation is determined genetically. Hence the genome gets its importance due to its capability to produce, specific types of protein for bringing out genetical characteristics.
The daily requirement of protein, according to the Nutrition experts committee of ICMR (Indian Council for Medical Research) and WHO (World Health Organisation) is 1 gm per kg body weight. Reduction in the intake of protein leads to protein malnutritions, such as marasmus and kwashiorkar. In marasmas the child loses weight and it also causes severe diarrhoea and the body muscles get wasted. It will appear as though the bones are covered by the skin. In kwashiorkar there is a wastage of muscles. Face and feet will have oedema. The belly region will appear enlarged.