A typical bacterial cell divides by the process of binary fission to produce daughter cells. Here, let us learn more about the process of bacterial cell division and the concept of generation time.
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Cell Division in Bacteria
Bacteria grow and reproduce by the process of binary fission. A bacterial cell begins to divide when the number of its cellular components reaches a critical mass. A circular double-stranded DNA molecule makes up the bacterial chromosome.
A cell cycle is made up of DNA replication, cell growth and cell division. The bacterial cell cycle can be classified into two parts:
- A DNA cycle that involves DNA replication and chromosome segregation.
- A division cycle that results in cytokinesis and cell separation.
In order to form the division septum, the cell must first distinguish the mid-cell site where division will take place, then differentiate this site in order to prepare for cytokinesis. This is done by coordinating with the rigid peptidoglycan layer (in the case of Gram-negative bacteria like E.coli, the outer membrane of the cell envelope) and the cytoplasmic membrane.
Also Check: Difference between Karyokinesis and Cytokinesis
Bacteria Cell Division – Process
FtsZ is an essential protein for the construction of the division apparatus and the process of cytokinesis. It is a tubulin-like protein that forms a ring at the location where bacteria will eventually divide. The ring is also called the Z-ring. The Z-ring is formed by smaller FtsZ filament subunits. To divide the cell, these filaments should pull against one another and tighten. The FtsZ-dependent binary fission is as follows:
- The two DNA strands are split apart and new complementary strands are created during replication. The result is the formation of two identical double-stranded DNA molecules.
- The two daughter cells receive the replicated DNA molecules.
- The cell membrane gives rise to a transverse septum that spreads across the entire cell.
- The two daughter cells then split after the deposition of cell wall material. This is induced by the development of Z-rings and FtsZ polymerization.
- Finally, entirely new organisms or new daughter cells are formed which feature tightly wound ribosomes, plasmids, and DNA rods.
FtsZ needs a cell wall to function. Only a little is known about how bacteria that do not normally produce a cell wall divide. It could be similar to the budding-like extrusion and separation.
Even after cell division, the daughter cells of some bacterial species may still be loosely connected. Since some daughter cells do not separate following cell division, they can be found as diplococci bacteria and in chains.
The generation time is the amount of time needed for a bacterium to produce two daughter cells under ideal circumstances. Most medically significant bacteria have a generation time of around 20 minutes. Some may even require 18 to 24 hours or more. Bacterial multiplication typically stops after a few cell divisions as a result of the depletion of nutrients and the buildup of harmful byproducts.
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