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Binary fission
From Wikipedia, the free encyclopedia
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Please help improve this article or section by expanding it. Further information might be found on the talk page or at requests for expansion. This article has been tagged since January 2007. |
Binary fission is the form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size, used by most prokaryotes. This process results in the reproduction of a living cell by division into two equal or near-equal parts.
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Binary fission begins with DNA replication. DNA replication starts from an origin of replication, which opens up into a replication bubble (note: prokaryotic DNA replication usually has only 1 origin of replication, whereas eukaryotes have multiple origins of replication). The replication bubble separates the DNA double strand, each strand acts as template for synthesis of a daughter strand by semiconservative replication, until the entire prokayotic DNA is duplicated.
Each circular DNA strand then attaches to the cell membrane, sometimes by a mesosome. The cell elongates, causing the two chromosomes to separate.
Cell division in bacteria is controlled by the septal ring, a collection of about a dozen proteins that collect around the site of division. There, they direct assembly of the division septum. [1]
The cell membrane then invaginates (grows inwards) and splits the cell into two daughter cells, separated by a newly grown cell plate. This process is called cytokinesis.
Binary fission is asexual; offspring are supposed to be genetically identical to the parent cell, but due to mutation, daughter cells may have slightly differed genetic makeups.
Bacterial DNA has a relatively high mutation rate. This rapid rate of genetic change is what makes bacteria capable of developing resistance to antibiotics and helps them exploit invasion into a wide range of environments.
Organisms that reproduce through binary fission generally have exponential growth phases. Escherichia coli cells are able to divide every 20 minutes under optimum conditions during their exponential growth phase.
Many organisms reproduce by binary fission, such as:
- Eubacteria
- Archaebacteria, such as Pyrodictium abyssi (an anaerobic thermophile of deep-sea hydrothermal vents)
Some eukaryotes reproduce using binary fission-like methods. Mitosis is thought to derive from binary fission.
This article contains material from the Science Primer published by the NCBI, which, as a US government publication, is in the public domain.
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