Chirality means having different left-handed and right-handed forms; not mirror symmetric. In the case of molecules, the existence of distinct right- and left-handed forms, known as enantiomers, is due to the molecule containing an asymmetric carbon atom. Chirality is an important property of life-supporting carbon compounds. Only right-handed carbohydrates and left-handed amino acids are metabolically active in Earth's organisms. Enzymes, which regulate a variety of biological processes, have the ability to recognize the desired chirality of a substrate. This enhances the versatility of carbon, though chirality is not limited to carbon compounds and occurs in most macromolecules.