Bacterial Physiology 2 Flashcards
What is fermentation?
A mode of energy yielding metabolism in which an the organic products derived from organic substrates serve as the primary electron donor and terminal electron acceptor.
Where does the energy from fermentation come from?
Glycolysis
What is the net yield per glucose by SLP in fermentation/
2 ATP; NADH is recycled.
Describe the fate of the substrate and product of fermentation.
Substrate is both oxidized and reduced; Not completely oxidized. Product(s) are excreted
Is there a Poly-A-cap or splicing of prokaryotic RNA?
NO
Describe the transcripts of prokaryotic RNA.
They are polycistronic.
What are the uses of sigma 70, 32, and 60 factors?
Sigma 70: General use
Sigma 32: Heat shock
Sigma 60: Nitrogen
What is a benefit of a polycistronic operon?
They allow coordinated expression of related genes; Multiple polypeptides can be made from a single mRNA.
What is the primary fuel source for bacteria?
Glucose; Will use lactose if glucose is not available.
Describe the regulation of the lac operon.
Lac repressor protein obstructs the operon when lactose is absent. If lactose is present, it binds the repressor protein and inactivates it with a conformational change.
Describe the positive regulation of the lac operon when glucose is absent.
When glucose is low, cAMP is high. CAP protein binds cAMP, this complex binds the promoter; Recruits RNA polymerase to the promoter thus increasing expression.
What is the purpose of he Trp operon?
To make Trp when there is not enough in the cell; Its required for protein synthesis.
Describe the Trp operon negative regulation.
If Trp is in excess of needed levels, TrpR binds Trp and Trp operator transcription is repressed. The reverse is true for when Trp levels are high.
Describe termination of bacterial protein synthesis.
Requires release factors RF 1,2 & 3. At the end of the last gene encoded, there will be a terminator structure that will cause the ribosome to dissociate from the mRNA.
