What are the building blocks of proteins?

• A. Nucleotides
• B. Amino acids
• C. Monosaccharides
• D. Fatty acids

Answer: (B)

Proteins are polymers built from amino acids linked together by peptide bonds through a dehydration synthesis reaction. Each amino acid has an amino group, a carboxyl group, a central carbon, and a variable side chain that gives each one unique properties. When amino acids join, the carboxyl carbon of one reacts with the amino group of the next, releasing a molecule of water and forming a peptide bond. The sequence of amino acids—the primary structure—determines how the chain folds into its three-dimensional shape and defines the protein’s function.

Nucleotides are the building blocks of nucleic acids (DNA and RNA), monosaccharides form carbohydrates (like glucose), and fatty acids are components of lipids (such as fats and membranes). Therefore, the building blocks of proteins are amino acids.