Which two functional groups are always found in amino acids?

• A. Carbonyl and amino groups.
• B. Carboxyl and amino groups.
• C. Amino and sulfhydryl groups.
• D. Hydroxyl and carboxyl groups.

Answer: (B)

Verified step by step guidance

1. Understand that amino acids are the building blocks of proteins and have a specific structure.
2. Recognize that each amino acid contains a central carbon atom (alpha carbon) bonded to four different groups.
3. Identify the two functional groups that are always present in amino acids: the amino group and the carboxyl group.
4. The amino group is represented as \($\mathrm{-NH}{2}_{}$\), which is a basic group.
5. The carboxyl group is represented as \($\mathrm{-COOH}$\), which is an acidic group.