Cell Division in Prokaryotes

Prokaryotes divide through a process called binary fission (which literally means 'splitting in two').

In prokaryotic cells, there is no nucleus and the DNA is free in the cytoplasm. This means that the process of cell division is a little simpler than it is in eukaryotic cells.

First, the DNA is replicated. A prokaryotic cell usually contains a single, circular chromosome. It may also contain some plasmids. Each of these DNA molecules is replicated to form two identical copies.

The different copies of each DNA molecule then go to opposite ends of the cell.

Finally, the cell membrane separates to form two cells. Each cell receives one copy of each DNA molecule.

Diagram of binary fission. At the top of the diagram there is a prokaryotic cell. There is an arrow pointing downwards from this cell, labelled "DNA replicated" and it points to a diagram of the same cell but with two copies of every DNA molecule. There is an arrow pointing downwards from this cell labelled, "DNA molecules move to opposite ends of cell". It points to a diagram of the same cell, but now the two copies of each DNA molecule have moved to opposite ends of the cell. There is an arrow pointing downwards from this cell labelled, "Cell splits in two" and it points to a diagram of two smaller cells, each with half of the DNA molecules from the previous cell.

Binary fission is the process by which prokaryotic cells divide.

The two cells that are formed are genetically identical to the original cell and to each other.

Prokaryotes are always unicellular, so they only use cell division for reproduction (there are no tissues to grow, maintain or repair). And reproduction in prokaryotes is always asexual.

If prokaryotes have enough nutrients and are at a suitable temperature, they can carry out binary fission very quickly. Some species of bacteria can divide by binary fission once every 20 minutes.

Time-lapse video of bacterial cells dividing. The video starts with one bacterial cell. This divides in two. Each of those cells then grows and divides in two and so on. The video was filmed over about 5 hours but has been sped up to a few seconds.

Time-lapse video of bacteria dividing. The bacteria are E. coli, which is a bacterium commonly found in the intestines of humans and many other animals. Image: Stewart EJ, Madden R, Paul G, Taddei F (2005) via Wikimedia Commons (CC BY-SA 4.0 - https://creativecommons.org/licenses/by-sa/4.0/deed.en)


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