Regulation of Gene Expression Flashcards
Operon
what is it a unit of? Found in
Includes what 3 things
Unit of genetic function found in bacteria /prokaryotes
Includes promoter, operator, and a cluster of genes.
Operator
Region of DNA that binds to repressor
Tryptophan
Amino acid
Turns gene expression on and off
When tryptophan is low
Repressor is inactive, operon is on, enzymes get made to make tryptophan
When tryptophan is high,
- Tryptophan binds to repressor, activating it.
- Repressor binds to operator
- Blocks RNA polymerase, Operon is off, and blocks transcription
- No enzymes made
Lactose can be a possible
fuel source for bacteria
Inducible Operon
Bound=repressor off
Unbound=active repressor
Like lactose
Besides lactose, _____ can be used by prokaryotes for energy. It is
Glucose
It is preferred when present
When glucose is scarce,
When glucose is present,
cAMP levels are high
cAMP levels are low
When lactose is present and glucose is not
Repressor is inactive
cAMP is high. cAMP binds to inactive CRP, activating it.
CRP Binds to promoter
Operon is expressed
When both lactose and glucose are present
Repressor is inactive
Glucose is high so cAMP is low.
Therefore CRP remains inactive.
RNA polymerase does not bind
Operon is not expressed.
Repressible vs inducible operon
Repressible- when tryptophan bound, repressor is active
Inducible- when lactose is bound, repressor is inactive
When neither lactose nor glucose is present
Repressor is active
cAMP is high. cAMP binds to inactive CRP, activating it.
CRP Binds to promoter
Operon is not expressed due to repressor.
Differentiation is when..by
It is necessary for
Where one cell type turns into another cell type. (By modifying gene expression)
Necessary for dev of multicellular organisms
Morphogenesis
Development of organs and body systems
