Chirality or handedness is a characteristic feature of living systems. Natural l-amino acids and d-ribose exemplify the preference for one particular mirror image form, called dextrorotary (d) and levorotary (l) enantiomeric configuration. Thus, an asymmetric or chiral carbon atom is one around which four different substituents can be arranged in left- or right-handed orientation. A chiral compound is present in two mirror image molecules (enantiomers). Extant life depends on chiral homogeneity for the structure and function of biopolymers.