Glycine. Molecular model of the amino acid glycine. Its chemical formula is C2.H5.N.O2. Atoms are represented as balls and are colour- coded: carbon (blue), hydrogen (gold), oxygen (red) and nitrogen (dark blue). Amino acids are the building blocks of proteins. Glycine has the simplest molecular structure of the amino acids. Glycine is a non-essential amino acid; it can be synthesised by the body and so does not need to come from the diet. Glycine is an important neurotransmitter, plays a large role in metabolism, and is integral to the formation of haemoglobin (the oxygen-carrying pigment in human blood). It is also used to synthesise adenine and guanine, two of the crucial molecules that make up an organisms' genetic material.