Question

Optical isomers are not observed for which of the following amino acids?

• A. Glycine
• B. Arginine
• C. Alanine
• D. Cysteine

Answer 1

The correct option is A Glycine

Glycine is simplest amino acid. In glycine, the substituted or R group is H. Hence, glycine has two hydrogens attached to the $\alpha$-carbon atom. Thus, glycine does not contain an asymmetric carbon atom. Hence glycine is optically inactive.

In all the other amino acids the $\alpha$-carbon atom is asymmetrical. Thus, all the other amino acids are optically active.