BIOL 111 Chapter Notes - Chapter 18: Trp Operon, Corepressor, Operon
Document Summary
Concept 18. 1: bacteria often respond to environmental change by regulating transcription. Natural selection has favored bacteria that produce only the products needed by that cell. Gene expression in bacteria is controlled by the operon model. The cluster of functionally related genes can be under coordinated control by a single. The regulatory switch is a segment of dna called an operator usually positioned within the promoter. An operon is the entire stretch of dna that includes the operator, the promoter, and the genes that they control. The operon can be switched off by a protein repressor. The repressor prevents gene transcription by binding to the operator and blocking rna polymerase. The repressor is the product of a separate regulatory gene. The repressor can be in an active or inactive form, depending on the presence of other molecules. A corepressor is a molecule that cooperates with a repressor protein to switch an operon off.