Molecular model of the Tyrosine (C3. 11. NO3), a proteinogenic non-essential amino acid synthetized from another amino acid called phenylalanine. The body requires tyrosine for many functions. In particular, this amino acid is closely linked to nervous system function, metabolism and regulating mood. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (white), nitrogen (blue) and oxygen. Illustration.