Question
Which of the following amino acids is not optically active?
Glycine
Valine
Leucine
Isoleucine
Solution
A.
Glycine
Glycine is the simplest and smallest amino acid. A compound is said to be optically active, when a chiral or asymmetrical carbon (ie, carbon attached to four different groups or atoms) is present. Since, chiral carbin is absent in glycine, it does not show optical activity. Other amino acids such as Valine, Leucine and Isoleucine etc contains atleast one chiral carbon, therefore, are optically active.
