Which Two Functional Groups are Always Found in Amino Acids

Question

Which two functional groups are always found in amino acids?
A) ketone and methyl
B) carbonyl and amino
C) carboxyl and amino
D) amino and sulfhydryl
E) hydroxyl and carboxyl

Accepted Answer

The carboxyl group (-COOH) and the amino group (-NH2) are always found in amino acids.

The other choices are incorrect:
A) Ketone (-C=O) and methyl (-CH3) groups are not always found in amino acids.
B) Carbonyl (-C=O) and amino (-NH2) groups are found in amino acids, but the carboxyl group is also present.
D) Amino (-NH2) and sulfhydryl (-SH) groups are not always found in amino acids.
E) Hydroxyl (-OH) and carboxyl (-COOH) groups are both present in some amino acids (such as serine), but not all amino acids.