gene regulation Flashcards
tryptophan operator: normally on or off?
normally on
operon
a functioning unit of genomic DNA containing a cluster of genes under the control of a single promoter.
tryp operon: negative or positive regulation?
negative regulation. controlled by a repressor protein - (aka normally, RNA polymerase is able to smoothly ride the RNA, but when something activates the repressor protein aka presence of tryptophan, it sits down and prevents RNA polymerase from sitting down
where would a repressor protein bind when it activates
the operator sequence on the DNA
activator protein
when an activator protein is present and active, it binds to an activator site on the RNA and turns genes ON
if you have an activator protein is this positive or negative regulation
positive
lac operon- normally on or off?
normally off
what two types of proteins control lac operon?
activator and repressor proteins
constitutive mutation
always on (lac operon)
CAP
catabolite activator protein- an activator protein that is itself regulated by the presence of glucose
how does glucose regulate CAP?
low glucose -> high CAP (promoter activated) and vice versa
how does lactose in the environment control the lac repressor
lactose -> allolactose -> allo binds 2 repressor, prevents it from sitting on the operator sequence like it normally does (recall lac normally off) and lets RNA sits down, begin transcribing enzymes to deal with lactose
what 2 things are necessary for lac operon to transcribe
CAP being in, and repressor not being on there
transcription factors
eukarytoes control gene expression via transcription factors, like TATA binding protein
enhancers
from a distance, tell transcription to go
