Amino acid

Amino acids were primitive proteins. (TV: The Stones of Blood) Types of amino acids included leucine, isoleucine, and methionine. (TV: Full Circle) They could be found in amniotic fluid (TV: City of Death) or primordial soup alongside sugars and proteins (TV: Ghost Light), where they formed minute cells that could eventually evolve into vegetable and animal life. (TV: City of Death)

Similarly, the Source contained methane, hydrogen, ammonia, amino acids, proteins and nucleic acids, which together could be used to accelerate evolution and make a barren planet habitable. (TV: The Doctor's Daughter)