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: Leucine, Isoleucine, Valine

Branched-chain amino acids (BCAAs) specifically refer to a group of three essential amino acids: leucine, isoleucine, and valine. These amino acids are characterized by their branched chemical structure, which distinguishes them from other amino acids. They play crucial roles in muscle metabolism, protein synthesis, and energy production, making them particularly important for athletes and individuals engaged in exercise. Leucine is known to stimulate muscle protein synthesis through various pathways, including the mTOR pathway, which is vital for muscle growth. Isoleucine contributes to energy production and is involved in metabolic regulation. Valine also aids in energy production and helps maintain nitrogen balance in the body. The other groups of amino acids mentioned do not fit the definition of branched-chain amino acids. Glutamine, glycine, and proline are not branched-chain amino acids, as they have different structures and functions. Similarly, tyrosine, phenylalanine, and tryptophan are aromatic amino acids, and alanine, arginine, and cysteine do not possess the branched structure characteristic of BCAAs. Understanding these classifications is essential for recognizing the unique roles that specific amino acids play in various physiological processes.