Amino acids

When taken up into the human body from the diet, the twenty two standard amino acids are either used to synthesize proteins and other biomolecules or oxidized to urea and carbon dioxide as a source of energy.^[29] The oxidation pathway starts with the removal of the amino group by a transaminase, the amino group is then fed into the urea cycle.

Essential	Nonessential
Isoleucine	Alanine
Leucine	Asparagine
Lysine	Aspartic Acid
Methionine	Cysteine*
Phenylalanine	Glutamic Acid
Threonine	Glutamine*
Tryptophan	Glycine*
Valine	Proline*
	Selenocysteine*
	Serine*
	Tyrosine*
	Arginine*
	Histidine*
	Ornithine*
	Taurine*

(*) Essential only in certain cases.

Amino acids are critical to life, and have many functions in metabolism. One particularly important function is as the building blocks of proteins, which are linear chains of amino acids.