Amino acid synthesis is the set of biochemical processes (metabolic pathways) by which the amino acids are produced. The substrates for these processes are various compounds in the organism's diet or growth media. Not all organisms are able to synthesize all amino acids.

• Primary amino acid synthesis: This is the synthesis of amino acids from simple precursors, such as alpha-ketoglutarate, pyruvate, and oxaloacetate. Primary amino acid synthesis is common to all organisms.

• Secondary amino acid synthesis: This is the synthesis of amino acids from other amino acids. Secondary amino acid synthesis is found in some, but not all, organisms.