Amino acids are the constituent subunits of proteins and represent an essential element of cell culture media. There are 8 essential amino acids in humans (Ileu, Leu, Lys, Meth, Phe, Treo, Trp, Val). As well as other amino acids whose synthesis capacity has been lost during the passage to in vitro such as Gln, Tyr, Cys, Arg and His.

Glutamine (Gln) is essential to almost all mammalian cell cultures, this essential amino acid is the major source of energy for cell proliferation. This amino acid is not stable in solution even at +4°C, so it must be added to the medium before use. Glutamine serves as a precursor for the synthesis of purines, pyrimidines, amino sugars and some amino acids. A glutamine deficiency can lead to a cell growth arrest due to an inhibition of DNA synthesis.