Endosymbiont

An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis (Greek: endo = inner and biosis = living). For instance, some nitrogen fixing bacteria (known as rhizobia) live in root nodules on legume roots, reef-building corals contain single-celled algae, and several insect species contain bacterial endosymbionts. Many other examples of endosymbiosis exist.

Related Topics:
Organism - Cell - Greek - Bacteria - Rhizobia - Root nodules - Legume - Corals - Insect

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Many instances of endosymbiosis are obligate, where neither the endosymbiont nor the host can survive without the other. One example is represented by gutless marine worms which can not survive without their endosymbiotic bacteria. However, not all endosymbioses are obligate. Also, some endosymbioses can be harmful to either of the organisms involved. See symbiosis for further discussion of this issue.

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It is generally agreed that certain organelles of the eukaryotic cell, especially mitochondria and chloroplasts, originated as bacterial endosymbionts. This theory is known as the endosymbiotic theory, confirmed and popularized by Lynn Margulis.

Related Topics:
Organelle - Eukaryotic - Mitochondria - Chloroplast - Endosymbiotic theory - Lynn Margulis

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