Aresearcher is trying to culture mouse embryonic stem cells, and is providing them with glucose (sugar) as a food source. in order for these cells to survive in culture, he must also add a mixture of essential amino acids to the culture medium. these essential amino acids are

It is a fact that there are nine essential amino acids, which are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

However, he needs to add at least twelve essential amino-acids to the culture for the cells to survive. They are: arginine, cystine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, histidine, tyrosine and valine.