Н H₂N-C-COOH CH2 CH2 CH₂ M OW Oc

Amino acids are chemical molecules that combine to produce proteins and are hence known as building blocks of proteins. They play important role in variety of biological and chemical functions in human body. Basic amino groups (-NH₂) and carboxyl group(-COOH)are found in amino acids. 

There are 20 amino acids in total that are used in the production of proteins. 

Amino acids are classified in 3 different categories: 

Essential amino acids, which are not produced by body but come from the food which we eat such as methionine, lysine, isoleucine, histidine, phenylalanine, tryptophan, valine, threonine and leucine. 

Non Essential amino acids, directly produced by the body such as alanine, asparagine, aspartic acid and glutamic acid. 

and other remaining amino acids are in conditional amino acids group which are not necessary on daily basis but important when we are injured or sick.