Main Entry: cis·tron Pronunciation: 'sis-"trän Function: noun : a segment of DNA that is equivalent to a gene and that specifies a singlefunctional unit (as a protein or enzyme) —cis·tron·ic/sis-'trän-ik/adjective
cistron cis·tron (sĭs'trŏn') n. The smallest functional unit of heredity; a length of chromosomal DNA associated with a single biochemical function and essentially equivalent to a gene.