L9 Regulation of gene expression Flashcards
How are metabolic pathways regulated at the protein level
feedback inhibition
How are metabolic pathways regulated at the gene level
control the production of an enzyme by regulating gene transcription
how are metabolic pathways regulated at the protein level
feedback inhibition
how are metabolic pathways regulated at the gene level
ctrl of the production of an enzyme by regulating gene transcription
what is feedback inhibition
Feedback inhibition involves the use of a reaction product to regulate its own further production. The cell responds to an abundance of the products by slowing down production during anabolic or catabolic reactions. Such reaction products may inhibit the enzymes that catalyzed their production
what are prokaryotic genes organized into
operons
what does operon ctrl
gene expression in bacteria
what does operon contain
gene that codes for proteins that function in same metabolic pathway
what do the genes in operon code for
proteins that function in same metabolic pathway
what is operon composed of
1- promoter
2- genes that will be ctrld
what is the promoter of the operon
- contains operator
- acts as an on/off switch
the genes that will be controlled in the operon are the genes of what
genes that code for all enzymes in same pathway
the genes in the operon, how are they transcribed
as a single mRNA, they are clustered and work together. they are controlled by the promoter
the mRNA produced by operon contains what
start/stop codons for each polypeptide
when an operon is ON:
- RNA polymerase…
transcription…
translation…
- RNA polymerase binds to promoter
- transcription occurs: all genes transcribed as 1 long mRNA
- translation occurs: production of all polypeptides (enzymes) in pathway
when operon is off: - - what happens to operator
- RNA pol…
transcription…
- repressor protein binds to operator
- rna pol can’t bind to promoter
- transcription blocked
advantage of operon existing in 2 states
all enzymes needed in metabolic pathway produced or turned off AT ONCE
where is the regulatory gene
upstream of operon promoter
what is the repressor protein produced by
regulatory gene
when is regulatory gene transcribed, and what does this mean for repressor prot
always transcribed= repressor protein always produced
the binding of a repressor to operator is —–
reversible
what kind of protein is repressor protein
allosteric protein, meaning having allosteric site
when the protein is in active conformation what does it do
binds to operator
when the protein is in inactive conformation what does it do
does not bind to operator
what is the activity of repressor protein dependant on
metabolites in cell (ex. tryptophan, allolactose)
