Which from following amino acids does NOT contain chiral carbon?

Step-by-step solution

The general structure of an -amino acid is H₂N-CH(R)-COOH . For an amino acid to be chiral, the -carbon must be attached to four different groups. In glycine, the side chain R is a hydrogen atom ( H ). The structure of glycine is H₂N-CH₂-COOH . Since the -carbon is attached to two identical hydrogen atoms, it does not have four different groups attached to it, making it achiral. Valine, alanine, and isoleucine have different R groups (isopropyl, methyl, and sec-butyl respectively) and thus contain chiral carbons. A