Practice question

Operon concept formulated by François Jacob and Jacques Monod describes cluster of functionally related structural genes arranged adjacently under control of single promoter and operator transcribed together as polycistronic messenger RNA. Operons often include genes encoding proteins in same metabolic pathway like lac operon lacZYA for lactose catabolism or trp operon for tryptophan biosynthesis. Regulatory protein repressor or activator binds operator modulating polymerase access, enabling coordinate response to environmental signals. Operon organization predominates in prokaryotes, providing efficient regulatory economy absent in most eukaryotes where genes individually regulated.