A polypeptide chain is a long sequence of amino acids linked together by peptide bonds. These chains are essential for the formation of proteins, which play crucial roles in biological processes. Each polypeptide has a unique sequence of amino acids that determines its specific function and structure. Polypeptide chains can fold into complex shapes, allowing them to perform various tasks in the body. The process of folding is influenced by the chemical properties of the amino acids and their interactions. Properly folded polypeptides are vital for the functionality of proteins, which are involved in everything from enzymes to hormones.