Amino acids are essential building blocks of proteins, which play a vital role in maintaining the structure and function of cells in living organisms. They are organic compounds that contain both an amino group (-NH2) and a carboxyl group (-COOH) on the same carbon atom.

There are 20 common amino acids that are found in proteins, each with a unique side chain. These 20 amino acids can be classified based on several criteria, such as their polarity, charge, and structure.

The first classification is based on the polarity of the side chain. Amino acids with polar side chains, such as serine and asparagine, can form hydrogen bonds with water molecules and are considered hydrophilic. On the other hand, amino acids with nonpolar side chains, such as valine and phenylalanine, cannot interact with water and are considered hydrophobic.

Another classification is based on the charge of the side chain. Amino acids with a positive charge, such as lysine and arginine, are called basic amino acids. Those with a negative charge, such as glutamic acid and aspartic acid, are called acidic amino acids. Amino acids with no net charge, such as glycine and alanine, are called neutral amino acids.

The third classification is based on the structure of the side chain. Amino acids with aliphatic side chains, such as glycine and alanine, have a straight chain structure. Amino acids with aromatic side chains, such as phenylalanine and tyrosine, have a ring structure. Amino acids with sulfur-containing side chains, such as cysteine and methionine, have a thiol group. Amino acids with hydroxyl-containing side chains, such as serine and threonine, have an alcohol group. Amino acids with amide-containing side chains, such as asparagine and glutamine, have an amide group.

Amino acids are synthesized in living organisms through a process called protein biosynthesis. Non-essential amino acids can be synthesized by the body, while essential amino acids have to be obtained from the diet. Amino acids can also be obtained through protein supplements and amino acid supplements.

In conclusion, understanding the organic chemistry of amino acids is crucial for understanding the functioning of proteins and living organisms. The 20 common amino acids can be classified based on their polarity, charge, and structure, which determines their properties and functions. By incorporating the right amino acids in your diet, you can ensure your body gets the necessary building blocks for protein biosynthesis and overall health.