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a collection of objects linked together in linear fashion, or end to end, as the assemblage of atoms or radicals in a chemical compound, or an assemblage of individual bacterial cells.
branched chain an open chain of atoms, usually carbon, with one or more side chains attached to it.
closed chain several atoms linked together so as to form a ring, which may be saturated, as in cyclopentane, or aromatic, as in benzene.
H chain (heavy chain) any of the large polypeptide chains of five classes that, paired with the L or light chains, make up the antibody molecule of an immunoglobulin; heavy chains bear the antigenic determinants that differentiate the classes of immunoglobulins. See also heavy chain disease.
J chain a polypeptide occurring in polymeric IgM and IgA molecules.
L chain (light chain) either of the two small polypeptide chains (molecular weight 22,000) that, when linked to H or heavy chains by disulfide bonds, make up the antibody molecule of an immunoglobulin monomer; they are of two types, kappa and lambda, which are unrelated to immunoglobulin class differences.
open chain a series of atoms united in a straight line; components of this series are related to methane.
chain reaction a chemical reaction that is self-propagating; each time a free radical is destroyed a new one is formed.
side chain a group of atoms attached to a larger chain or to a ring.
chain re·ac·tion(chān rē-ak'shŭn)
A self-perpetuating reaction in which a product of one step in the reaction itself serves to bring about the next step in the reaction, and so on.