The word "polypeptid" is a scientific term that refers to a long chain of amino acids. Its pronunciation is /pɒlɪˈpɛptɪd/, with emphasis on the second syllable. The spelling of "polypeptid" follows the standard English convention where the letter "y" changes to "i" when adding suffixes or forms compound words. In this case, "poly-" means many, and "-peptide" means a chain of amino acids. Therefore, "polypeptid" describes a long chain of amino acids made up of many small peptide units.
A polypeptide refers to a chain or a sequence of amino acids that are joined together by peptide bonds. It is essentially a polymer, a larger molecule formed by the linking of smaller subunits, in this case, amino acids. Amino acids are organic compounds that serve as the building blocks of proteins.
Polypeptides are integral components of proteins, which are essential macromolecules for various cellular functions. They are involved in numerous biological processes, including enzymatic reactions, transport of molecules, cell signaling, and structural support.
The length of a polypeptide chain can vary significantly, ranging from a few amino acids up to thousands of amino acids in length. The specific order and arrangement of these amino acids dictate the unique properties and functions of the resulting protein.
Polypeptides are generated through a process called translation, which occurs during protein synthesis. During this process, the ribosome reads a messenger RNA (mRNA) molecule and uses the information encoded in it to construct the polypeptide chain by joining the appropriate amino acids together.
Overall, polypeptides are crucial constituents of proteins, contributing to their diverse functionality in living organisms. Their structural diversity and ability to form different types and shapes of proteins allow for a vast range of biological activities and physiological roles within cells and organisms.
A peptid formed by the union of more than three amino-acids.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "polypeptid" is derived from two roots: "poly" and "peptid".
1. "Poly": The prefix "poly-" comes from the Greek word "polus", meaning many or much. It is often used to indicate quantity or multiplicity. In the context of "polypeptid", "poly-" refers to the presence of multiple amino acids linked together.
2. "Peptid": "Peptid" is derived from the Greek word "peptos", which means digested or broken down. In biology, it refers to a short chain of amino acids linked together by peptide bonds. The suffix "-id" in "peptid" is used to denote a substance belonging to a certain group or category.