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
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統計: A(0), B(0), C(0), D(0), E(1) #3332988
統計: A(0), B(0), C(0), D(0), E(1) #3332988