MHTCET 17 Apr 2026 Shift 1 Paper

Concept:A chiral carbon is a carbon atom attached to four different groups.Explanation:Most $\alpha$-amino acids have the general structure $\mathrm{NH}_2-\mathrm{CH}(\mathrm{R})-\mathrm{COOH}$. In this structure, the central carbon is bonded to four groups: $\mathrm{NH}_2$, $\mathrm{COOH}$, $\mathrm{H}$, and the R group. When all four groups are different, the carbon is chiral. Glycine has the simplest R group, which is just hydrogen. Therefore, the structure of glycine is $\mathrm{NH}_2-\mathrm{CH}_2-\mathrm{COOH}$. Here, the central carbon is attached to two hydrogen atoms, along with $\mathrm{NH}_2$ and $\mathrm{COOH}$. Since two groups are identical, the carbon is not chiral. Thus, glycine is the only amino acid among the given options that does not contain a chiral carbon. Valine, alanine, and isoleucine have different R groups, so their central carbons remain chiral.Answer:Option C: Glycine