A polypeptide is a chain of amino acids linked together by peptide bonds. These chains are essential building blocks for proteins, which play crucial roles in the body, such as supporting cell structure, facilitating chemical reactions, and regulating processes. Each polypeptide has a unique sequence of amino acids that determines its specific function and shape. When a polypeptide folds into a specific three-dimensional structure, it becomes a functional protein. The process of folding is influenced by various factors, including the environment and the presence of other molecules. Understanding polypeptides is vital in fields like biochemistry and molecular biology, as they are fundamental to life.