Binary fission — asexual cellular division in prokaryotes and protists
Binary fission is a simple asexual division that produces two daughter cells from one parent; it is the principal means of reproduction for many bacteria and some single-celled eukaryotes.
Binary fission, literally "division in half," is an asexual process by which a single cell splits to form two daughter cells. It is the primary reproductive method of many single-celled organisms, especially prokaryotes, and is common among bacteria. Some single-celled eukaryotes such as Amoeba and Paramecium also reproduce by binary fission. Because the process does not involve the fusion of gametes, it is classified as asexual reproduction.
Basic mechanism
At its simplest, binary fission follows a few ordered events: the cell duplicates its genetic material, partitions those copies to opposite sides of the cell, and then divides the cytoplasm to make two new cells. The initial step is DNA replication of the single chromosome or of multiple chromosomes in protists. In many bacteria the circular chromosome is copied from a defined origin and the copies move apart as the cell elongates. The physical dividing of the cell involves constriction of the cell envelope and formation of a septum; the cell membrane and, where present, cell wall components are remodeled to produce two separate compartments.
Steps and components
- Genome duplication: the cell makes a full copy of its DNA.
- Segregation: replicated genomes are sorted so each future daughter will receive one copy.
- Cytokinesis: the cell divides, completing the separation into two cells.
In many bacteria specialized proteins coordinate these steps; for example, cytoskeletal elements guide constriction and septum placement so division is roughly symmetrical.
Prokaryotic versus eukaryotic contexts
Although the outcome—two cells from one—is the same, binary fission in prokaryotes is generally simpler than division in multicellular eukaryotes. Eukaryotic cells with multiple linear chromosomes undergo a more complex sequence called mitosis followed by cytokinesis. Even so, some single-celled eukaryotes reproduce by a binary-like division in which chromosome replication and segregation are coordinated within a different cellular architecture.
Genetic consequences and significance
Daughter cells produced by binary fission are ordinarily genetically identical to the parent cell, aside from any copying errors. Spontaneous mutations that occur during replication create genetic variation that can be acted on by natural selection. In prokaryotes, additional mechanisms such as the transfer of plasmids and other mobile elements can alter genetic makeup after division, so clonal populations are not necessarily genetically uniform.
Binary fission enables rapid population increase under favorable conditions and underlies many ecological and medical phenomena, from blooms of microbes to the spread of antibiotic-resistant strains. It is also the basis for cultivating bacteria in laboratory and industrial settings, where controlled binary fission produces biomass or biochemical products.
For a more detailed comparison of the molecular machinery and regulation in different groups of organisms, see specialist sources and reviews on asexual reproduction and summaries of DNA replication and cell division in prokaryotes and eukaryotes.
Questions and answers
Q: What is binary fission?
A: Binary fission is a form of asexual reproduction in which a single parent cell splits into two daughter cells with identical genetic material.
Q: What organisms use binary fission for reproduction?
A: Binary fission is most commonly used by prokaryotes such as bacteria, and some single-celled eukaryotes like the Amoeba and Paramoecium.
Q: How does binary fission work?
A: During binary fission, the fully grown parent cell replicates its genetic material and then divides into two equal sized daughter cells. The DNA molecule divides and forms two molecules that move towards opposite sides of the bacterium while the cell membrane also divides to form two daughter cells. After division, the new cells grow and the process repeats itself.
Q: Is mitosis similar to binary fission?
A: While both processes involve splitting one cell into two, mitosis is more complicated than binary fission since it occurs in eukaryotic tissue cells.
Q: Are mutations possible during replication in binary fission?
A: Yes, mutations can occur during replication in binary fission which would make the resulting daughter cells genetically different from each other.
Q: Does every organism use binary fission for reproduction?
A: No, not all organisms use binary fusion for reproduction; some organisms reproduce through sexual means or other forms of asexual reproduction such as budding or fragmentation.
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AlegsaOnline.com Binary fission — asexual cellular division in prokaryotes and protists Leandro Alegsa
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