試題詳解

3. Of the 20 standard amino acids, only ______ is not optically active. The reason is that its side chain ______.
(A) alanine； is a simple methyl group
(B) glycine； is a hydrogen atom
(C)glycine； is unbranched
(D) lysine； contains only nitrogen
(E) proline； forms a covalent bond with the amino group