A polypeptide is a chain of amino acids linked together by peptide bonds. These chains can vary in length and sequence, determining the specific function of the polypeptide in biological processes. Polypeptides are essential building blocks of proteins, which play critical roles in the structure and function of cells. In the body, polypeptides are synthesized through a process called translation, where the genetic code from DNA is used to assemble the amino acids in the correct order. Once formed, polypeptides can fold into complex shapes, allowing them to perform various functions, such as acting as enzymes or hormones.