Zusammenfassung der Ressource
Control of gene expression in Prokaryotes
- Enzymes
- Inducible
- Constitutive
- Repressible
- Regulation control
- Positive
- Negative
- Regulatory elements
- Cis-acting
- Trans-acting
- Lac operon
- Structural genes
- lacZ
- lacY
- lacA
- Negative control
- Transcription only occurs when the repressor fails to bind to the operator region
- Model
- Proved by analysis of lac
expression in the absence
or presence of lactose in
partial diploid merozygotes
- Catabolite activating protein
- Involved in catabolite repression
- repress expression of the lac
operon when glucose is present
- In the absence of glucose
and presence of lactose, CAP
exerts positive control
- binding the CAP-binding
site and facilitating RNA
polymerase binding at the
promoter
- Cyclic adenosine monophosphate
is required for CAP binding
- Glucose represses expression of adenylyl cyclase
- the enzyme that catalyses the production of the trp structural genes
- Trp operon
- Transcription can occur even
when the operon is repressed in
the presence of tryptophan