Cell division Flashcards
Asynchronous cultures
Culture with cells at different points of the cell cycle
Synchronous cells
Culture with cells at the same points in the cell cycle
Ideal for studying
Induction methods
- Growth after nutrient starvation
- Change in temperature
- Growth inhibitor
significant metabolic disturbance but high cell yield
Selection methods
Size
Age
Baby machine
Selection by age mechanism
Cells divide into funnel
Collected at intervals - same age and therefore synchronous
Conditionally lethal mutants
Mutants that can grow under permissive conditions but die under restrictive conditions e.g. temp sensitive mutants
System 1 genes
Involved in increasing cell size
System 2 genes
Involved in creating cylindrical rod shape
System 3 genes
Involved in cell division w formation of new septum
Diffuse intercalation
Gram positive: Cell gets larger by additional of new cell wall material all over cell wall
Gram negative: E.coli by putting materially equally in interior of cell wall = expansion of cell
FtsZ
Prokaryotic homologue of eukaryotic tubulin
GTPase
Divisome
FtsZ + other proteins e.g. ZipA, Ftsl that cause cell separation
ZipA
Anchors FtsZ to cell membrane
FtsA
ATPase - depolarisation + constriction of z-ring
FtsI
Transpeptidase involved in crosslinkng PG to cell wall
FtsK
Separates chromosomes
How is septum location controlled?
Min proteins
Dichotomous/multi fork replication
DNA-A
Replication initiator
binds to ATP for active form and then binds to DNA-A box
DNA-A box
AT rich region to which DNA-A binds to
Facilitates unwinding of DNA
Frequency of replication is controlled by…?
The availability of DNA-A in ATP form
RIDA
Regulatory Inactivation of DNA-A
DAM
DNA adenine methylase
Methylates A and recognises GATC domains in oriC
SeqA
Membrane bound protein
Binds to new hemimethylated sequencr
Pulls apart chromosomes when cell divides
