What is composed of one or more polypeptides?

• A. Amino acid
• B. Polypeptide
• C. Protein
• D. Enzyme

Answer: (C)

A protein is composed of one or more polypeptides. Polypeptides are long chains of amino acids that are linked together by peptide bonds. Once a polypeptide chain folds into a specific three-dimensional shape, it becomes a functional protein. Proteins are essential macromolecules that perform a wide range of functions in biological systems, including catalyzing biochemical reactions, providing structural support, and transporting molecules.

While individual polypeptides themselves can exist, they typically need to fold and associate with others to form a complete protein. Therefore, the defining characteristic of proteins is that they can be made up of one or more polypeptides, distinguishing them from other molecules such as amino acids or enzymes. Enzymes, which are also proteins, are one specific type of protein that serves as biological catalysts but do not define the broader category of proteins in general.