Bacterial Cell Division Flashcards
Which viruses intefere with host G0/G1 transition and how?
Influenza A Coronaviruses EBV They do this by inducing G0/G1 arrest
What is the advantage to viruses inducing G0/G1 arrest?
Creates more favourable conditions for virus replication, due to less competition for resources and reduced immune response
What are the different cell cycle stages for bacteria?
B period - cell growth C period - chromosome replication D period - cell division
What happens to the the cell cycle under rapid growth conditions?
The previously mentioned processes overlap
What can some bacteria like E. coli do?
Multifork replication, which involves initiating a new round of chromosome replication before the previous round is complete
How does peptidoglycan synthesis occur in gram -tve and +ve bacteria?
Synthesis starts in the cytoplasm, then continues to the cytoplasmic membrane. It finishes in the periplasm for gram -tve, or outside the cell for gram +tve
How is new peptidoglycan incorporated into the existing sacculus?
By cutting and pasting mechanism
What is the difference between how gram -tve and +tve bacteria split?
Gram -tve = synthesise and split the septum simultaneously (constriction) Gram +tve = synthesise complete septum, then split
Compare how E. coli, S. aureus and S. pneumoniae grow their peptidoglycan cell wall
E. coli (rod): lateral growth, producing elongated rod shape
S. aureus (coccus): limited lateral growth around whole cell plus septal growth, producing circular shape
S. pneumoniae (ovococcus): peripheral & septal growth, producing oval shape
What is the main difference between bacterial and eukaryotic cell cycle phases?
Bacterial cell cycle phases are not as discrete- a lot of overlap (e.g. multifork replication)
What is Mreb?
Actin homologue that is only present in rods, not in cocci. It is required for rod shape
What is FtsZ?
Tubulin homologue that forms Z rind at mid cell, and recruits other proteins of the divisome; peptidoglycan septum is then synthesised
What are the two ways in which bacterial cells divide, wrt examples?
The bacterial cell divides via constriction of the membrane at division site (E. coli, S. pneumoniae) or due to hydralases breaking down cell wall at division site and mechanical ‘popping’ (S. aureus)
How is the divisome positioned in rods (e.g. E. coli)
Min system prevents formation of Z-ring at the cell poles by creating a gradient of inhibitory proteins that oscilate from pole to pole. Nucleoid occlusion prevents the Z-ring from forming over the nucleoid, to ensure cell division does not bisect genetic material
How is the divisome positioned in staphylcocci (S. aureus)?
Combination of chromosomal segregation and nucleoid occlusion to ensure division machinery only assembles after chromosomes have been properly segregated
