Amino acid: the basic structure of proteins

Amino acid is the name given to the basic structural unit of proteins. Nitrogen molecules are combined with hydrogen molecules to make what is called an amino group. All amino acids contain at least one amino group (-NH2) in the alpha position and one carboxyl, and all (except Glycine) contain an asymmetric carbon atom. For this reason, they may exist as isomers.

Amino acids have what is called an R group, which is a side group that distinguishes one amino acid from another.

Most naturally occurring amino acids are of the L-configurations, although D-amino acids are not uncommon in some microorganisms.

The presence of a D-amino acid oxidase in mammalian tissue, however, suggests that the D-forms may play some yet unrecognized role in mammalian protein metabolism.

Amino acids enter into the general metabolic path ways which have been called anabolism and catabolism. 

Every aspects of physiology involves proteins. Individual amino acids serve as neurotransmitters, hormones, and modulator of various physiological processes.

Nine of amino acids are called essential amino acids, because human body cannot make them and must get them though diet. The body can manufacture the remaining 11 amino acids, called nonessential amino acids. 

Consuming the essential amino acids presents no problem to people who regularly eat proteins containing ample amounts of al the essential amino acids such as those of meat, fish, poultry, cheese, eggs, milk and most soybean products.

When amino acid backbones joined end to end, a protein forms. The bonds that from between adjoining amino acids are called peptide bonds. Proteins often contain from 35 to several hundred or more amino acids.
Amino acid: the basic structure of proteins