MB 351 Lecture 37: 10.5 Positive Control and Global Control
Document Summary
Structural genes efg: only synthesized if maltose available, require maltose activator protein to join the activator binding site upstream of promoter (i site) Inactive if no maltose: active is maltose, the inducer, binds to it, activator protein recruits polymerase to join at promoter, global control in catabolite repression, respond to change in env, regulate many diff genes at once. Lactose not used because cells cannot transport and cleave disaccharide lactose. Lactose used next in less steep exponential line: diauxic growth, two different growth phases, glucose is preferred bc uses less enzymes and is best energy source. Important regulatory phenomena: 5-10% of bacterial genes do this. Important for natural selection bc it determines which carbon source is used and that determines growth and competitive success. For lactose to be used and broken down : glucose must not be present (positive control) camp is made, crp attaches and causes transcription of lac genes which breakdown lactose.
