What is the building block of proteins?

• A. Amino Acid
• B. Monomer
• C. Carboxyl Group
• D. Hydroxyl Group

Answer: (A)

Proteins are polymers made from amino acids, the building blocks that determine their structure and function. Each amino acid features an amino group and a carboxyl group attached to a central carbon, plus a unique side chain that gives it different properties. The amino acids are linked together by peptide bonds—the bond forms between the carboxyl group of one amino acid and the amino group of the next, releasing a molecule of water. The order of amino acids creates a polypeptide that folds into a specific shape required for its role in the cell. While a monomer is a general term for the single unit in many polymers, and carboxyl or hydroxyl groups are functional groups found in many molecules, the actual building blocks of proteins are amino acids.