| Revision as of 17:38, 20 August 2006 editNeutrality (talk | contribs)Autopatrolled, Administrators165,397 edits New | Revision as of 17:41, 20 August 2006 edit undoNeutrality (talk | contribs)Autopatrolled, Administrators165,397 edits NanobesNext edit → | ||
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| The majority of ] consider ]es to be non-living because they lack a ]ular structure and cannot ] by themselves, requiring a host cell to replicate and synthesise new products. A minority of scientists hold that because viruses do have ] they can be considered as organisms. The smallest ]es in terms of ] size are small ]es such as ] with genomes of 3.5 kb and particle diameters of 80 ]. The smallest ]es are the ] such as ], at 3.2 kb and 42 nm; ]es have smaller ]s, at 18-26 nm, but larger genomes, at 5 kb. The smallest DNA ] is the ], thought to be larger than Hepatitis B, at about 4 kb. | The majority of ] consider ]es to be non-living because they lack a ]ular structure and cannot ] by themselves, requiring a host cell to replicate and synthesise new products. A minority of scientists hold that because viruses do have ] they can be considered as organisms. The smallest ]es in terms of ] size are small ]es such as ] with genomes of 3.5 kb and particle diameters of 80 ]. The smallest ]es are the ] such as ], at 3.2 kb and 42 nm; ]es have smaller ]s, at 18-26 nm, but larger genomes, at 5 kb. The smallest DNA ] is the ], thought to be larger than Hepatitis B, at about 4 kb. | ||
| ==Nanobes== | |||
| ]s are the current undisputed smallest known organism, about ten times smaller than the smallest known bacteria. Nobes, tiny filamental structures first found in some rocks and sediments, are ten times smaller than the smallest known ] and were first described in 1996 by Philipa Uwins of the ]. The smallest are 20 nm long. Some researchers believe them to be merely ] growths, but a purported find of ] in nanobe samples may prove otherwise. They are similar to the life-like structures found in ], the famous ] ] from the ]. | |||
| {{seealso|Largest organism}} | {{seealso|Largest organism}} | ||
Revision as of 17:41, 20 August 2006
The smallest organism found on Earth can be measured using a variety of different methods, and can be defined as the smallest by volume, mass, height, or length. Because there is some dispute over what the definition of life is and what entities qualify as organisms, the actual "smallest organism" may be unclear.
Viruses
The majority of biologists consider viruses to be non-living because they lack a cellular structure and cannot metabolize by themselves, requiring a host cell to replicate and synthesise new products. A minority of scientists hold that because viruses do have genetic material they can be considered as organisms. The smallest RNA viruses in terms of genome size are small retroviruses such as rous sarcoma virus with genomes of 3.5 kb and particle diameters of 80 nm. The smallest DNA viruses are the hepadnaviruses such as Hepatitis B, at 3.2 kb and 42 nm; parvoviruses have smaller capsids, at 18-26 nm, but larger genomes, at 5 kb. The smallest DNA bacteriophage is the Phi-X174 phage, thought to be larger than Hepatitis B, at about 4 kb.
Nanobes
Nanobes are the current undisputed smallest known organism, about ten times smaller than the smallest known bacteria. Nobes, tiny filamental structures first found in some rocks and sediments, are ten times smaller than the smallest known bacteria and were first described in 1996 by Philipa Uwins of the University of Queensland. The smallest are 20 nm long. Some researchers believe them to be merely crystal growths, but a purported find of DNA in nanobe samples may prove otherwise. They are similar to the life-like structures found in ALH84001, the famous Mars meteorite from the Antarctic.
See also: Largest organism