How was Lac Operon Function Investigated?
First gene regulatory system to be understood at molecular level
Jacob and Monod inserted F’ plasmids into E. coli to create partial diploids
Inhibitor protein from I gene diffusible
Functional I gene on one lac operon strand will repress transcription on both
(provided both operators unmutated)
Promoter/operator complex only controls genes downstream on same strand
This is cis-dominance
Which Kind of Gene Regulation Does the Lac Operon Demonstrate?
Multiple genes controlled by single promoter
I gene repressor protein binds to operator to block transcription – removed by
Transcription rate greatly increased by cAMP/CAP complex binding to promoter
Eukaryote vs Prokaryotic Genome Structure and Organization