Biology 1002B Lecture Notes - Lecture 13: Lac Repressor, Catabolite Activator Protein, Operon
19 Mar 2016
School
Department
Course
Professor
Document Summary
The on/off control of genes occurs at the transcriptional level. An operon is a cluster of prokaryotic genes and the dna sqs involved in their regulation. Recall that the promoter is a region where dna polymerase begins transcription. Another regulatory dna sq in the operon is the operator. Some operons are controlled by a regulatory protein known as a repressor. When the repressor is bound to the dna it decreases the likelihood that genes will be transcribed. Other operons are controlled by a regulatory protein called an activator. When the activator is bound to the dna it increase the likelihood that genes will be transcribed. Many operons are controlled by more than 1 regulatory mechanism, and also; a number of repressors/activators control more than 1 operon: this complex network of control of transcription allows almost instantaneous global responses to changing environment conditions.
