Proteins are bio-molecules which serve a lot of functions in our body. The various functions of proteins are as under : -
1) Enzymatic function : Majority of enzymes in our body are proteins. Enzymes help in speeding up a biochemical reaction in our body. For example, catalase helps in decomposition of hydrogen peroxide into water and oxygen thereby protecting our body from oxidative damage.
2) Structural function : Many structural parts in our body are made up of proteins. For example, our hair and nails are made up of keratin which is a type of protein.
3) Transportation : Many proteins transport materials from one part of our body to another part of our body. For example, hemoglobin transports oxygen in our body.
Even though there are only a limited number of different amino acids yet a wide variety of proteins exist in an organism. It is possible because the arrangement/sequence and number of amino acids differs in different type of proteins.