bacteria reproduce by binary fission , which is a single cell, divides into two identical daughter cells. it occurs through formation of the Z ring that recruits additional proteins to form the septa ring.

1. BACTERIAL CELL
DIVISION
SUBMITTED BY: SHUBHANGI KANSAL
SUBMITTED TO: DR. DHUNI CHAND
M.SC. MICROBIOLOGY 1ST SEMESTER

2. REPRODUCTION
 All types of macromolecules double in amount
 Proteins
 RNA and DNA
 Lipids for membranes
 Cell wall components
 Small organic and inorganic molecules
 In general, the materials are evenly distributed to each daughter cell.
 Each daughter cell contains : ½ old cell material & ½ new cell
material
 All biosynthetic events must be carefully coordinated.

3. CELL DIVISION
 CELL DIVISION is pre programmed in 3- dimensions. It occurs in a
spatial & temporal context:
• DNA repicates
• Formation of the FtsZ ring and cell elongation
• DNA partitions aided by Divisome
• A cell septum forms
• The daughter cells then separate

4. BACTERIAL CELL DIVISON OCCUR
BY “BINARY FISSION”
 In a growing rod shaped cell, elongation
continues until the cell divides into two new cells;
called BINARY FISSION .
 Cells elongate to approximately twice their
original length & then forms a partition (SEPTUM)
that separates the cell into two daughter cells.
 Results from the inward growth of the cytoplasmic
membrane & cell wall from opposite directions,
which continues until the two daughter cells
pinched off.
 When one cell divides to form two, one generation
has occurred, & the time required for this process
is called the GENERATION TIME.

6. THE DIVISOME
 Several essential proteins play roles in cell
division in Bacteria. Collectively,
 these proteins are called Fts proteins and a key
one, FtsZ,
 plays a crucial role in binary fission.
 Fts proteins interact in the cell to form a division
apparatus called the divisome.
 Fts stands for Filamentous Temperature
Sensitive .

7. The FtsZ ring appears & disappears
during cell division

8. MinCD & nuclear occlusion act together to
prevent Z-ring assembly midcell
 Cell elongation & nucleoid segregation alleviate
nucleoid occlusion.
 Min C is recruited to the membrane by MinD.
Membrane localisation of Min C is necessary for
FtsZ inhibition to occur.
 Min E is responsible for keeping the MinCD complex
from acting in the midcell region, thus enabling the
formation of Z-ring in the proper location.
 Min E oscillates from pole to pole , keeping the zone
of MinCD inhibition at the poles, & not at midcell.

9. MinD oscillation in E.coli allows
formation of Z-ring in the center of
the cell

10. Divisome and Cell Division

11. PEPTIDOGLYCAN SYNTHESIS
 Synthesis of new peptidoglycan during growth requires the controlled cutting of
preexisting peptidoglycan along with the simultaneous insertion of peptidoglycan
precursors.
 A lipid carrier molecule called bactoprenol plays a major role in the latter process.
Bactoprenol is a hydrophobic C55 alcohol that is bonded to an N-acetylglucosamine/N-
acetylmuramic acid/ pentapeptide peptidoglycan precursor. BACTOPRENOL transports
peptidoglycan precursors across the cytoplasmic membrane by rendering them
sufficiently hydrophobic to pass through the membrane.
 Once outside the cell, the bactoprenol complex interacts with enzymes called
transglycosylases that insert peptidoglycan precursors into a growing point in the cell wall
and catalyze glycosidic bond formation.
 Prior to this, small gaps in the existing peptidoglycan are made by enzymes called
autolysins, New cell wall material is then added across the gaps.
 Peptidoglycan synthesis must be a highly coordinated process and peptidoglycan
precursors must be readily available during autolysin activity. This is because tetrapeptide
units must be spliced into existing peptidoglycan immediatelyafter autolysin activity in
order to prevent a breach in the peptidoglycan at the splice point; a breach could cause
spontaneous cell lysis, called autolysis.

13. REFERENCES
 BROCK BIOLOGY OF MICROORGANISMS by Madigan Martinko
Dunlap Clark (Pearson Internatinal Edition)