3. Trancription Flashcards
what is the mRNA called when genes of related function are often clustered together and transcribed from a single promoter and what are the genes known as?
polycistronic mRNA
operon
Name 4 examples of global regulatory systems in E.coli
SOS response
heat shock
aerobic respiration
catabolite repression
What does LacZ encode?
beta galactosidase
What does lacY encode?
beta galactoside permease
What does LacA encode?
Beta galactoside transacetylase
What does lacI encode
The lac repressor
What are the 3 important features of the 182 bp intragenic region?
Lac P- promotor
Lac O - operator
CAP site - where the cAMP acceptor protein binds
what does the Lac repressor binding (Lac O) site overlap?
Lac P
How is the lac repressor inactivated?
The presence of lactose leads to the formation of allolactose by beta galactosidase
The binding of allolactose to each of the 4 repressor (LacI) subunits causes an allosteric change of shape and it is no longer bound to LacO
What is often used in molecular studies to activate the lac promoter ?
IPTG
How is CAP activated?
It requires activation of cAMP which is formed when ATP is converted by adenyl cyclase
When glucose is absent adenyl cyclase becomes activated
What recruits RNA pol to the weak promoter?
7 amino acid surface-exposed beta-turn of CAP and the alpha CTD of RNA pol
Describe the two types of phage vectors?
Insertion vectors - non essential DNA is removed and DNA can be cloned into this site
Replacement vectors - non essential DNA is replaced with non coding DNA that can be replaced by the San to be cloned
Name two examples of regulation of expression by ncRNAs
- addiction cassettes
2. regulation of iron-containing genesis E.coli
What does global regulator FUR repress?
RhyB
