6.5 Gene Regulation in prokaryotes Flashcards
Prokaryotes must be able to _____ which genes are expressed at any given time
Regukate
How can genes be turned on or off?
Based on environmental and internal cues
What does turning a gene “on” or “off” mean? What does this allow for?
Whether or not transcription will take place
- cell specialization
What are operons?
- a group of genes that can be turned on or off
What are the three parts of operons?
- Promoter
- operator
- genes
What is the promoter of an operon?
- where RNA polymerase can attach
What is the operator of an operon?
The on/off switch
What do genes do in an operon?
Codes for related enzymes in pathways
Operons can be _____ or ______
Repressive or inducible
What does repressible operons mean? (2)
- on to off
- transcription is usually in, but can be repressed, or stopped
What does an inducible operon mean? (2)
- off to on
- transcription is usually off, but can be induced, or started
What is a regulatory gene? (2)
- produces a repressor protein that binds to the operator to block RNA polymerase from transcribing the gene
- always exposed, but at low levels
Is binding of a repressor to an operator reversible?
Yes
The trp operon is a _____ (repressible/inducible) operon.
Repressible
What does the trp operon control?
- controls the synthesis of tryptophan in bacteria