Question

All naturally occuring alpha-amino acids are optically active except glycine.Why?

Answer 1

An optically active molecule is an unsymmetrical molecule and contains a chiral atom. Amino acids have a carbon atom at the center or alpha position and for the amino acid to be chiral or optically active, this carbon atom should be surrounded by four different elements/molecules.

Glycine is the only amino acid that has two hydrogen atoms attached to the central or alpha carbon atom and thus is achiral or optically inactive.