LIFE 102 Lecture Notes - Operon, Enzyme Inhibitor, Repressor
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. A cell can regulate the production of enzymes by feedback inhibition or by gene regulation. Gene expression in bacteria is controlled by the operon model. A cluster of functionally related genes can be under coordinated control by a single on- off switch . 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.
