L18 - bacterial gene regulation pt.2

operon

the group of structural genes, their promoter and additional sequences that control their transcription

promoter

site for transcription initiation, binds to the RNA polymerase enzyme

regulator protein

a protein that binds to another DNA sequence and controls the transcription of one or more structural genes.

can a operator sequence have a missense mutation? why?

no, missense occurs in protein coding regions but this sequence is made of noncoding DNA

operator sequence

regulatory region of DNA, near the promoter.

binds specific repressors, not to be translated into amino acids.

the operator sequence does not experience mutations. T/F

False, it can have a frame shift mutation to a base substitution mutation

the operator sequence affects the ….

rate of of transcription of the structural genes

the negative control RP is a

repressor

binds to DNA & inhibits transcription

RP

regulatory protein

the positive control RP is a

activator

binds to DNA and promotes transcription

what are the 2 types of transcriptional control in bacteria?

negative (repressor) and positive (activator)

Inducible operons

transcription starts off and something has to happen for it to be turned on

negative inducible operons

(no inducer present)

active repressor protein binds to the operator of an operon which physically blocks the RNA polymerase enzyme from binding to the operator

result = no transcription

negative inducible operons

(inducer present)

a small molecule binds to the active repressor protein to change its shape making it unable to bind to the operator

result = transcription takes place

corepressor

small molecule that binds to the inactive repressor protein change its shape so that can bind to DNA and inhibits transcription

repressible operon

transcription is normally on but but something must happen to turn it off

negative repressible operon

( no Product U)

inactive repressor cant bind to the operator

result = transcription takes place

negative repressible operon

(Product U)

product u binds to the inactive repressor protein and prevents transcription

product u is an example of a..

corepressor

what is lactose permease ?

active transport protein for lactose

what2 molecules does lactose break down into?

glucose and galactose

What is beta-galactosidase?

Enzyme that breaks down lactose and turns it into allolactose.

lactose metabolism is a example of ___ ___ _____

negative inducible operon

lactose metabolism

(lactose absent)

starts with a active repressor that binds to the

results unexpressed structural genes

lactose metabolism

(lactose pressent)

starts with a active repressor that becomes inactive when allolactise binds to it

result = protein doesnt bind to lacO operator and transcription and translation happens

what is the goal of E.coli metabolism

produce energy with as little waste as possible