How Important is Protein in Our Diet?

How Important is Protein in Our Diet?: "The word 'protein' is derived from the Greek word 'proteios', which means primary or holding first place. The way name suggest this group of components are the most important cell constituent. Protein is present in all cells of the body. It is present in variable level in different tissues of the body like muscles contain about 20% where as in blood plasma it is 7%."