Proteins are complex molecules that are formed from Amino Acids. They are considered as one of the most essential elements for the living cells. Basic function of Protein is to provide growth and repair to body cells. They also provide necessary energy source to the body.

There are different kinds of proteins. Monomeric proteins are molecules that are consist of one polypeptide chain. A protein which is consisted of more than polypeptide chains is called Oligomeric.
Scientists have also defined Proteins based on their chemical composition and are basically divided into two large groups or classes. Simple proteins are only composed of simple amino acids and include some organic and inorganic groupings while the subjugated proteins, the other class of proteins, include carbohydrates.
Proteins are also classified on their biological functions. Proteins include Enzymes which are being used by the body as a catalyst to expedite certain reactions of different living cells.
Proteins which are obtained from meat and milk are considered as most complete Proteins because they contain all the necessary amino acids. Vegetables are considered as the second important source of proteins but not as reliable as meat and milk because some essential amino acids are not found in vegetables.