Bacterial Cell Cycles

What are the three main steps of the bacterial cell cycle?

initiation mass reaches, initiation of replication, and septum formation begins when z-ring forms

draw out and describe the parts of the bacterial cell cycle

What is the partitioning system?

The machinery bacteria use to make sure the two newly replicated chromosomes are separated and moved into opposite halves of the cell before division

What is parS?

specific DNA sequences near the origin of replication

summarize what happens in the partitioning system, draw it out.

1. DNA replication duplicates parS/oriC sites in chromosome

2. ParB binds to ParS

3. ParA directs one ParB-ParS complex toward the opposite pole

4. the rest of the chromosome follows as the replication continues

what is the min system in septum formation?

set of proteins

oscillates between the two cell poles where it spends most of its time

prevents FtsZ polymerization at the poles

what is nucleoid occlusion in septum formation?

proteins that are attached to the chromosome

prevents Z-ring formation over the bacterial chromosome

allows Z-ring formation only after the two nucleoids have separated

draw out what happens in septum formation

Describe what FtsZ, FtsA, and ZipA do in septum formation

FtsZ polymerizes into z-ring at midcell

FtsA and ZipA attach the Z-ring to the plasma membrane

FtsA also helps recruit additional cell-division proteins

draw out the cross section of a bacillus cell during septum formation

What does the divisome do in septum formation?

made of divisome proteins that assemble around the z-ring

begins septal peptidoglycan synthesis that will become the new cell walls for the daughter cells

what is the first step in peptidoglycan synthesis?

Synthesis of the NAG-NAM- pentapeptide building block is completed in the cytoplasm while it is attached to a lipid carrier, bactoprenol, located in the plasma membrane.

What is the second step in peptidoglycan synthesis?

The carrier- bound building block is then flipped across the membrane by a protein called MurJ

What is the third step of peptidoglycan sythesis?

Upon its release into the periplasmic space, the NAG-NAM pentapeptide is inserted into a peptidoglycan strand by enzymes termed peptidoglycan glycosyltransferases (GT). Strands are crosslinked by enzymes termed transpeptidases (TPases). TPases are also called penicillin-binding proteins.

Draw out what happens in peptidoglycan synthesis