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Prokaryotic Gene Regulation - Coggle Diagram
Prokaryotic Gene Regulation
Operons
Regulatory Elements
Trp Operon
induceable or repressible
genes code for enz that make trp
gene usually ON; repressor usually inactive
repressor binds to operator when trp HIGH
when repressor is activated by TRP (corepressor), it has high affinity for operator
repressor binds = RNAP can't transcribe bc steric hindrance = RNAP dissociates = no trp made
Lac Operon
HIGH Lactose NO glucose
LacI inactivated by allolactose (inducer)
RNAP transcribes = lactose metabolism happens = LacZ which isomerases lactose -> allolactose
allolactose inactivates LacI again
LOW lactose YES glucose
LacI always active, high aff for operator = steric hindrance for RNAP = transcription doesn't happen
No Lac metab enzymes = no lactose metabolized
CAP site
activator protein = increases transcription rates
usually inactive
cAMP = CAP's inducer
1) HIGH [glucose] inhibits Adenylyl cyclase
2) AC inhibited = cAMP doesn't get made
3) Therefore; HIGH glucose = LOW cAMP
LOW glucose = cAMP binds to CAP to activate it
activated CAP binds to CAP site
increases aff btwn RNAP and promoter = higher txn rate
end result= metabolism of lactose
4) CAP stays inactive, doesn't bind to CAP site
transcription is LOW
end result = lactose NOT metabolized