Gene Regulation Flashcards
Why is gene regulation necessary (2)
Inefficient to express all genes all the time - save energy
Some genes are only needed at certain times in certain environments
What is the term used for genes that are expressed continuously
Constitiutive/Housekeeping genes
How are Inducible and repressible genes different
Inducible - Inducer will cause the gene to be expressed
Repressible - Corepressor will inhibit the expression of the gene
What proteins are induction and repression regulated by and where do they bind on the DNA
Transcriptional regulatory proteins
DNA binding domain
Regulatory proteins either have negative or positive control - outline both
Negative - Binding inhibits initiation of transcription - repressor protein
Positive - Binding promotes initiation of transcription - activator protein
Where do repressor and activator proteins attach
Repressor - operator
Activator - activator binding sites
Negative transcriptional control on an inducible gene in absence and presence of inducer
In absence - Repressor protein will block transcription
In presence - Inducer prevents repressor from binding to DNA and transcription occurs
Negative transcriptional control on a repressible gene in absence and presence of corepressor
In absence - Repressor cannot bind to DNA and transcription occurs
In presence - Corepressor interacts with repressor which can now attach to DNA and transcription is blocked
Positive transcriptional control on an inducible gene in absence and presence of an inducer
In absence - Activator cannot bind to DNA and transcription is blocked
In presence - Activator interacts with inducer and binds to DNA so transcription occurs
Positive transcriptional control on a repressible gene in the absence and presence of corepressor
In absence - Activator binds to DNA and transcription occurs
In presence - Activator cannot bind to DNA and transcription is blocked
How does the Lacl repressor protein prevent transcription
Binds to the DNA and alters it shape preventing RNA polymerase to bind to the promoter
What binds to the repressor protein when lactose is present
Allolactose
What are the 3 structural genes in the Lac operon
LacZ
LacY
LacA
