Editing Biopolymer (section)

== Biopolymers versus synthetic polymers ==

A major defining difference between '''biopolymers''' and '''synthetic''' polymers can be found in their structures. All polymers are made of repetitive units called [[monomer]]s. Biopolymers often have a well-defined structure, though this is not a defining characteristic (example: [[lignocellulose]]): The exact chemical composition and the sequence in which these units are arranged is called the [[primary structure]], in the case of proteins. Many biopolymers spontaneously fold into characteristic compact shapes (see also "[[protein folding]]" as well as [[secondary structure]] and [[tertiary structure]]), which determine their biological functions and depend in a complicated way on their primary structures. [[Structural biology]] is the study of the structural properties of biopolymers. In contrast, most synthetic polymers have much simpler and more random (or stochastic) structures. This fact leads to a molecular mass distribution that is missing in biopolymers. In fact, as their synthesis is controlled by a template-directed process in most ''in vivo'' systems, all biopolymers of a type (say one specific protein) are all alike: they all contain similar sequences and numbers of monomers and thus all have the same mass. This phenomenon is called [[monodispersity]] in contrast to the [[polydispersity]] encountered in synthetic polymers. As a result, biopolymers have a [[dispersity]] of 1.<ref>Stupp, S.I and Braun, P.V., "Role of Proteins in Microstructural Control: Biomaterials, Ceramics & Semiconductors", ''Science'', Vol. 277, p. 1242 (1997)</ref>