Reexamining the Riddle of Homochirality

Optically active, or chiral, molecules make up the food we consume, parts of our homes and clothes, and every cell in our bodies. Every organism on our planet owes its existence to the way its molecules rotate plane-polarized monochromatic light. Depending on the particular optical molecule, it either rotates the polarized light to the right, dextrorotatory, or left, levorotatory. Such chiral molecules typically can be depicted as one of two mirror-images that are not superimposable (Fig. 1).