Ch. 15 Flashcards
What is gene expression?
the process by which genes get “turned on” to make RNA and proteins in a cell
What is the operator?
(in transcription)
it is the “on or off switch” near the start of an operon
where an active repressor can attach
What is an operon?
- a group of genes operating together
- consists of a promoter, operator, and other clusters of genes
- regulates other genes responsible for protein synthesis
What is a promoter?
the specific region of a gene where RNA polymerase can bind and begin transcription
What is a repressor?
- a protein that inhibits gene transcription
- binds to the promoter in prokaryotes
What is a regulatory gene?
a gene that codes for a repressor in order to control gene transcription
What are genes of the operon?
- the entire stretch of DNA required for all the enzymes produced by the operon
- genes that are going to be expressed
also called structural genes
What is tryptophan?
an amino acid needed by bacteria for survival
Is the trp operon innately turned off or on?
turned on; it is a repressible system
What is trpR?
a regulatory gene that binds to the operator and inhibits RNA synthesis
*in the trp operon
What happens when tryptophan is PRESENT?
trp repressor binds to the operator and RNA synthesis is blocked
What happens when tryptophan is ABSENT?
trp repressor detaches from the operator and RNA synthesis can proceed
What is lactose?
milk sugar available to E. coli when they come into contact with dairy
Is the lac operon innately turned off or on?
turned off; it is an inducible system
What is Lacl?
a regulatory gene that codes for a repressor protein, of which can switch the lac operon off
