Question

Assertion (A): All naturally occurring α-amino acids except glycine are optically active.

Reason (R): Most naturally occurring amino acids have L-configuration.

Options

• Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

• Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

• Assertion (A) is true, but Reason (R) is false.

• Assertion (A) is false and Reason (R) is true.

Answer 1

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

Explanation:

The optical activity results from the asymmetric structure present in alkyl-substituted α-amino acids, rather than from their L-configuration.

\[\begin{array}{cc}
\ce{H\phantom{....}H\phantom{...}O\phantom{...}}\\
|\phantom{.....}|\phantom{.....}||\phantom{..}\\
\ce{\underset{group}{\underset{Amino}{H-N}}-\ce{C -\underset{group}{\underset{Carboxyl}{C-OH}}}}\\
|\phantom{...}\\
\ce{\underset{Side chain}{R}\phantom{...}}
\end{array}\]