Microbiolgy Lecture 12 Flashcards
What are the mechanisms of gene regulation?
Constituitive
Inducible
Repressible
What’s a constitutive enzyme?
An enzyme that is always produced, gene expression is always on
What is an repressible enzyme?
An enzyme that is normally produced, but can be turned off when not needded
What is a inducible enzyme?
An enzyme that is not always produced, but can be turned on when needed
What are operons?
A cluster of multiple genes that are transcribed together, but translated seperatedly
What turns on gene expression?
Regulatory protein
What is a lac operon
Contains genes necessary to break down lactose
What is lac operon consider and why?
It’s considered inducible because it’s usually turned off, but can be turned on in presence of lactose and absence of glucose
What are the four genes in the lac operon?
Permease, B galactosidase, acetylase, and regulatory protein
During diphasic growth, E coli prefers to metabolize .. and then switch to …
It prefers to metabolize glucose and when no more glucose is present, switch to lactose
Why is there a pause in the Diphasic growth?
To turn lac operon on
What are riboswitches?
They regulate gene expression after transcription through binding of a ligand/ binding of ligand can hide or reveal Shine Dalgarno
What are sRNas
short noncoding RNAS that regulate translation
- They increase/decrease translation of a transcript
What two items regulate gene expression on a global scale
- Alternative sigma factor
- Secondary Messagers
Secondary Messagers involve what?
cAMP and ppGpp
What is cAMP?
Made when ATP levels are low/ increases expression of genes necessary for breaking down sugars
What is ppGpp
Made when amino acid levels are low/ Increases genes necessary to provide amino acids
In the absence of cAMP, what happens?
CAP does not bind the promoter/Transcription occurs at low rate
In the presence of cAMP, what happens?
CAP binds the promoter and increases RNA polymerase activity
What do cAMP CAP complex do?
They stimulate RNA polymerase activity and increases RNA synthesis
However, even in the presence of cAMP CAP, what happens?
- RNA synthesis is blocked
Talk about Individual behavior
Bacteria has individual behavior and act alone
Talk about Group behavior bacteria
Group Behavior leads to a bigger population, higher concentration, and leads to group behavior as bacteria communicate with one another and exhibit new group behaviors
When quorum has been reached, what happens?
Genes for a certain behavior are turned on
The lac operon is an example of .. gene expression
Inducible gene expression
What does alolactose do?
Bind to represor and prevent it from binding to lacO
What do transcriptional repressors do?
Block transcription by preventing RNA polymerase from activating transcription
Lac operons are turned on when?
In the presence of lactose
Lac Operon does what
Encodes proteins necessary for metabolizing lactose
