Is alanine a zwitterion?

Alanine (C₃H₇NO₂) exists as a zwitterion at physiological pH 7.3.

At this pH two things happen simultaneously. The α-amino group gets protonated to yield a positively charged ammonium group while the α-carboxyl group is separated to yield a negatively charged carboxylate ion. These two charges balance out, so the net charge on alanine is zero.