Prokaryotic Transcriptional Regulation Flashcards
As bacteria enables a metabolic shift to lactose, ___________ and ______ __________ increase
beta galactosidase, lactose permease proteins
What is the function of beta galactosidase
cleaves lactose into glucose and galactose
What is an operon?
A cluster of related genes with similar functions found in prokaryotes, controlled by an operator
What does an operon consist of?
-Promoter
-Operator
-Coordinated gene cluster
A/an _______ is a sequence near the start of the operon that can _____ or ________ transcription depending on whether it is bound to an inhibitor
Operator, allow, inhibit
The lac operon regulates _______ and __________ expression in e. coli
Beta galactosidase, lactose permease
The _______ binds the RNA polymerase complex in an operon
promoter
What is lacO
operator
What is lacY
lactose permease
What is lacZ
beta galactosidase
What is lacI
repressor protein
___________ regulated transcription involves a repressor protein that inhibits transcription, required genes are turned off
Negatively
The _____ gene is __________ expressed at low levels
lacI, constitutively
Are beta galactosidase and lactose permease produced when glucose is present? Why or why not?
No, a repressor binds the operator
How does the repressor protein for the lac operon work?
-Tetrametric protein made of 4 subunits
-Binds tightly to the operator and twists DNA into a loop
-Prevents RNA polymerase from binding when glucose is in use
How is negative regulation allosterically inhibited when the cell switches to metabolizing lactose?
-Lactose binds to the repressor protein
-Lactose acts as an inducer molecule and changes the protein conformation
_________ regulation of the lac operon promotes production of ____________ and ____________
Positive, beta galactosidase and lactose permease
A decrease in glucose causes an increase in intracellular _______ levels, which contributes to _______ regulation
cAMP (cyclic adenosine monophosphate), positive
When is adenyl cyclase inhibited? What does this do?
When glucose levels are high
Prevents the enzyme from catalyzing cAMP from ATP, resulting in low cAMP levels
What is the cAMP receptor protein?
-Involved in positive regulation
-When bound by cAMP will bind to the CAP-cAMP binding site
What is positive transcriptional regulation?
A transcriptional activator protein binds to an activator binding site, allowing RNA polymerase to bind
