NANP Board Practice Exam

Which amino acids are classified as branched-chain amino acids (BCAAs)?

1. Glutamine, Glycine, Proline

2. Leucine, Isoleucine, Valine

3. Tyrosine, Phenylalanine, Tryptophan

4. Alanine, Arginine, Cysteine

The correct answer is: Glutamine, Glycine, Proline

Branched-chain amino acids (BCAAs) are specifically characterized by their unique structure, which includes a branching aliphatic side chain. The primary BCAAs are leucine, isoleucine, and valine. These amino acids are essential, meaning they must be obtained through the diet, as the body cannot synthesize them. BCAAs play significant roles in muscle metabolism and are known to promote muscle growth, reduce exercise fatigue, and aid in recovery after exercise. They are particularly important for athletes and those engaged in intense physical training. In contrast, the other groups of amino acids listed do not qualify as branched-chain amino acids. Glutamine, glycine, and proline are categorized differently based on their structures and functions. Similarly, tyrosine, phenylalanine, and tryptophan are aromatic amino acids, while alanine, arginine, and cysteine serve distinct roles and do not have the branched structure characteristic of BCAAs. Thus, the choice that includes leucine, isoleucine, and valine is correct as it correctly identifies all three amino acids that are classified as branched-chain amino acids.