Bacterial cell division

Question 1

How are the steps of the cell cycle co-ordinated?

Answer 1

-initiation of DNA replication controls coordination of growth, replication and division (ie. replication happens fixed amount of time after DNA replication starts)

Question 2

How is the rate of DNA synthesis controlled?

Answer 2

-by conc of ribonucleotide reductase
-by alarmones ppGpp and ppGppp inhibiting primase DnaG

Question 3

How is cell size controlled according to the sizer mechanism?

Answer 3

cells grow to an average size (regardless of birth size) and then divide
-cell monitors size and must reach minimal size before cell cycle continues

Question 4

How is cell size controlled according to the adder mechanism?

Answer 4

cells grow by a constant(/conserved) amount between birth and dividing

Question 5

What is the divisome?

Answer 5

protein complex responsible for cell division (incl the constriction of membranes and synth of peptidoglycan at site of division)
eg. in E.coli. ring of filaments forming in centre (due to scaffold prot FtsZ) dictates where cells will divide

Question 6

How is the site of cell division selected in E.coli?

Answer 6

-unspecific binding to block nucleoid
-oscillating positioning system
-TER linkage system
-DNA translocase