True about charge in amino acid ?

Ans. is 'c' i.e., Neutral at isoelectric pH The pH value at which the number of positive charges equals the number of negative charges is isoelectric pH of amino acids. At its isoelectric pH, an amino acid is in zwitterion form (dipolar molecule), i.e. has both positive and negative charge on same acid, but overall molecule is electrically neutral. The carboxy (-COON) group of an amino acid can donate protein (Er) and behave as an acid forming a negatively charged anion (coo). Amino group (-N1-12) can accept proton (I-1+) and behave as a base, forming positively charged cation (NH3'). Amphoteric propey of amino acid Substances having a two-way propey are called amphoteric or ampholyte. Amino acids have both acidic and basic groups, i.e., they can donate a proton or accept a proton, hence amino acids are referred to as amphoteric. Amphoteric propey is related to : ? Zwitterion or dipolar molecule Monoamine-Monocarboxylic amino acids exist as dipolar ion or zwitterions, i.e., they have both positive and negative charges on the same amino acids. The a-COOH group donate its proton to amino group (-NH2) and becomes negatively charged anion (C00). The a-NH2 group accepts proton from carboxyl group (a-COOH) to form positively charged cation (NH3'). The overall molecule (zwitterion) is electrically neutral, i.e., the molecular species which contain an equal number of ionizable group of opposite charge and as a result bear no charge (are neutral) are called zwitterions.