Bacterial cell division 2 Flashcards
Difference between OD and viable cell count during exponential phase?
OD is higher–> overestimates
Difference between OD and viable cell count during stationary phase?
Viable count is higher–> OD underestimates
Bacteriostatic antibiotics and their total and viable cell count?
Stops bacteria from growing, does not kill them–> diff between total cell count and viable cell count is the same (neither drops)
Bacteriolytic antibiotics and their total and viable cell count?
Lyses cells–> total and viable cell count are the same
Both decrease
Bactericidal antibiotics and their total and viable cell count?
Kills cells w/o lysing them
Total cell count plateaus while viable cell count drops
What is present in the cytoplasm?
RNA, plasmids, ribosomes, cytoskeleton, enzymes, small molecules, nutrients
What does chromosome organisation need to take into account?
Replication
What is spatiotemporal organization?
The chromosome moving around as cells grow and divide
Bacterial cell cycle?
Gell growth
DNA rep
Chromosome segregation
Division into daughter cells
What grows during cell growth phase of replicaiton?
Cytoplasm and cell wall–> volume of the cell
What is protein localization?
Proteins being targeted to specific locations in the cell
Where could some proteins localize to?
One or both poles inod shaped cells (4 movement) or the midcell 4 cell division
What complex is responsible for DNA replication in bacteria?
Replisome
Where is the replication termination region?
Opposite the oriC
What is the replication region called?
terC
How do replication termination regions work?
They have permissive and non-permissive directions–> will allow replication going one direction over them but not the other
Tus protein binds to the Ter
Blocks DNA polymerase
Which protein binds to ter sites for replication termination
Tus
When can bacteria undergo multiple rounds of replication initiation?
In growth media where the carbon source is v efficient
Why do bacteria undergo multiple rounds of replication initiation?
So the cell can grow more quickly than they can replicate chromosomes
When does chromosome segregation occur?
WHile replication is occurring
What is the divisome?
The machinery necessary to cut the two daughter cells in half
How does the divisome work?
Z ring contracts around the middle of the cell
Stages of cell splitting?
Z ring formed down middle of the cell
Formation of mature divisome
Constriction and synthesis of inward septum
Cytokinesis completion
Cell separation
How does the Z ring only form at the midline?
Nucleoid occlusion
How does nucleoid occlusion work?
SMLA protein binds to diff sequences within the genome
Stops formation of the Z ring
Z ring can only form where SLMA isn’t
SLMA is on outside of DNA
therefore z ring can only form down the middle
What makes up the Z ring?
ftsZ
Where does ftsZ co-localise to?
The midcell
How does ftsZ constrict?
It is a GTP binding protein
What is ftsZ tethered to the membrane by?
ftsA and zipA
What is unique ab C.jejuni?
Has a flagellum so has to divide away from the pole where the flagellum is present
How do marine ectosymbionts divide?
Along the long edge of the cell
