Mutation

Abstract

A gene produces its biological effects by serving as a template for the formation of a gene product, usually a polypeptide, which is biologically active (e.g., as an enzyme or a structural protein.) The activity of the gene product is controlled by the sequence of amino acids in its structure; and this, in turn, is controlled by the sequence of the purine and pyrimidine bases in the structure of the gene. We will define a mutation as a permanent, heritable change in the structure of a gene, i.e., a change in the sequence of its bases, whether by rearrangement or deletion of existing bases, or by substitution or addition of new bases. Such a change may effect a change in the structure of the gene product, altering its activity. This in turn may cause a change in the metabolism, morphology and/or behavior of individuals carrying the mutant in homozygous condition (and sometimes in heterozygous condition as well.)