BSC 197 Lecture Notes - Lecture 24: Lac Operon, Catabolite Activator Protein, Catabolism
Document Summary
Prokaryotes and eukaryotes alter gene expression in response to their changing environment. In multicellular eukaryotes, gene expression regulates development and is responsible for differences in cell types. Rna molecules play many roles in regulating gene expression in eukaryotes. Bacteria often respond to environmental change by regulating transcription. Transcription is when most regulation occurs: dna is compact so depending on how compact it is affects regulation, proteins that are bound to dna affects how dna is transcribed or not. 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 (elongation) by binding to the operator and blocking rna polymerase.