Gene Regulation in Prokaryotic cells (Lactose and Tryptophan) Flashcards
Lac Operon
regulates the metabolism of lactose within the bacterial cell
structural genes of lac operon
Lac Z, Lac Y, Lac A
what enzyme do the structural genes code for (lac operon)
Beta-galactosidase (breaks down lactose)
where is upstream of the operon gene
repressor gene
when is Lac Operon active
when lactose is present in the cell
lac operon repressor protein
LacI
if RNA polymerase binds to the promoter why does the repressor affect it
because the promoter and operator overlap
what happens when lactose is present
lactose will bind the repressor causing it to change shape, releasing from the operator, allowing RNA polymerase to do its job (activate the gene)
- this makes lactose the inducer
Tryptophan in bacteria
non-essential amino acid and can be manufactured if not obtained in the diet.
structural genes for the TRP operon
5 genes in total required
when is the TRP operon active
when tryptophan is absent from the cell
what happens when tryptophan is absent
the repressor is inactive allowing RNA polymerase to synthesize tryptophan
what happens when tryptophan is present
tryptophan binds to the repressor activating it so it cannot bind to the operator stopping RNA polymerase from transcribing
- tryptophan is the corepressor
