Unicellular organism lacking a membrane-bound nucleus
Diagram of a typical prokaryotic cell
A prokaryote (/proʊˈkærioʊt,-ət/, also spelled procaryote)[1] is a single-cell organism whose cell lacks a nucleus and other membrane-bound organelles.[2] The word prokaryote comes from the Ancient Greek πρό (pró) 'before' and κάρυον (káruon) 'nut, kernel'.[3][4] In the two-empire system arising from the work of Édouard Chatton, prokaryotes were classified within the empire Prokaryota.[5] But in the three-domain system, based upon molecular analysis, prokaryotes are divided into two domains: Bacteria (formerly Eubacteria) and Archaea (formerly Archaebacteria). Organisms with nuclei are placed in a third domain, Eukaryota.[6]
Prokaryotes evolved before eukaryotes, and lack nuclei, mitochondria or most of the other distinct organelles that characterize the eukaryotic cell. It was once thought that prokaryotic cellular components were unenclosed within the cytoplasm except for an outer cell membrane, but bacterial microcompartments, which are thought to be quasi-organelles enclosed in protein shells (such as the encapsulin protein cages), have been discovered,[7][8] along with other prokaryotic organelles.[9] While being unicellular, some prokaryotes, such as cyanobacteria, may form colonies held together by biofilms, and large colonies can create multilayered microbial mats. Others, such as myxobacteria, have multicellular stages in their life cycles.[10] Prokaryotes are asexual, reproducing via binary fission without any fusion of gametes, although horizontal gene transfer may take place.
Molecular studies have provided insight into the evolution and interrelationships of the three domains of life.[11] The division between prokaryotes and eukaryotes reflects the existence of two very different levels of cellular organization; only eukaryotic cells have an enveloped nucleus that contains its chromosomal DNA, and other characteristic membrane-bound organelles including mitochondria. Distinctive types of prokaryotes include extremophiles and methanogens; these are common in some extreme environments.[2]
^"Definition of PROCARYOTE". www.merriam-webster.com. Retrieved 2023-12-30.
^ abNC State University. "Prokaryotes: Single-celled Organisms".
^Campbell, N. "Biology:Concepts & Connections". Pearson Education. San Francisco: 2003.
^"prokaryote". Online Etymology Dictionary.
^Sapp, J. (2005). "The Prokaryote-Eukaryote Dichotomy: Meanings and Mythology". Microbiology and Molecular Biology Reviews. 69 (2): 292–305. doi:10.1128/MMBR.69.2.292-305.2005. PMC 1197417. PMID 15944457.
^Coté G, De Tullio M (2010). "Beyond Prokaryotes and Eukaryotes: Planctomycetes and Cell Organization". Nature.
^Kerfeld CA, Sawaya MR, Tanaka S, Nguyen CV, Phillips M, Beeby M, Yeates TO (August 2005). "Protein structures forming the shell of primitive bacterial organelles". Science. 309 (5736): 936–8. Bibcode:2005Sci...309..936K. CiteSeerX 10.1.1.1026.896. doi:10.1126/science.1113397. PMID 16081736. S2CID 24561197.
^Murat D, Byrne M, Komeili A (October 2010). "Cell biology of prokaryotic organelles". Cold Spring Harbor Perspectives in Biology. 2 (10): a000422. doi:10.1101/cshperspect.a000422. PMC 2944366. PMID 20739411.
^Murat, Dorothee; Byrne, Meghan; Komeili, Arash (2010-10-01). "Cell Biology of Prokaryotic Organelles". Cold Spring Harbor Perspectives in Biology. 2 (10): a000422. doi:10.1101/cshperspect.a000422. PMC 2944366. PMID 20739411.
^Kaiser D (October 2003). "Coupling cell movement to multicellular development in myxobacteria". Nature Reviews. Microbiology. 1 (1): 45–54. doi:10.1038/nrmicro733. PMID 15040179. S2CID 9486133.
^Sung KH, Song HK (July 22, 2014). "Insights into the molecular evolution of HslU ATPase through biochemical and mutational analyses". PLOS ONE. 9 (7): e103027. Bibcode:2014PLoSO...9j3027S. doi:10.1371/journal.pone.0103027. PMC 4106860. PMID 25050622.
A prokaryote (/proʊˈkærioʊt, -ət/, also spelled procaryote) is a single-cell organism whose cell lacks a nucleus and other membrane-bound organelles. The...
wall Capsule Pili Marine prokaryotes are marine bacteria and marine archaea. They are defined by their habitat as prokaryotes that live in marine environments...
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unavailable. Prokaryotes, including bacteria and archaea, vary greatly in how they obtain nutrients across nutritional groups. Prokaryotes can only transport...
of circular DNA, unlike the linear chromosome of most eukaryotes. Most prokaryote chromosomes contain a circular DNA molecule – there are no free ends to...
cytoskeleton is the collective name for all structural filaments in prokaryotes. It was once thought that prokaryotic cells did not possess cytoskeletons...
animals (including protists), plants (also including algae and fungi) and prokaryotes (bacteria and archaea), is Latin and binomial in form; this contrasts...
An extremophile (from Latin extremus 'extreme', and Ancient Greek φιλία (philía) 'love') is an organism that is able to live (or in some cases thrive)...
The International Code of Nomenclature of Prokaryotes (ICNP) or Prokaryotic Code, formerly the International Code of Nomenclature of Bacteria (ICNB) or...
traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different...
origins. The genes in prokaryotes are often organized in operons, and do not usually contain introns, unlike eukaryotes. Prokaryotes do not possess nuclei...
In prokaryote nomenclature, Candidatus (abbreviated Ca.; Latin for "candidate of Roman office") is used to name prokaryotic taxa that are well characterized...
60% rRNA and 40% ribosomal proteins, though this ratio differs between prokaryotes and eukaryotes. Although the primary structure of rRNA sequences can...
antibiotics. A possible transitional form of microorganism between a prokaryote and a eukaryote was discovered in 2012 by Japanese scientists. Parakaryon...
Phototrophs (from Ancient Greek φῶς, φωτός (phôs, phōtós) 'light', and τροφή (trophḗ) 'nourishment') are organisms that carry out photon capture to produce...
general categories: prokaryotic organisms and eukaryotic organisms. Most prokaryotes are unicellular and are classified into bacteria and archaea. Many eukaryotes...
only from a single specimen, described in 2012. It has features of both prokaryotes and eukaryotes but is apparently distinct from either group, making it...
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Prokaryotes (ICSP), formerly the International Committee on Systematic Bacteriology (ICSB), is the body that oversees the nomenclature of prokaryotes...
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"solitary") is historically a biological kingdom that is made up of prokaryotes. As such, it is composed of single-celled organisms that lack a nucleus...
asexually, as in single-celled organisms such as bacteria and other prokaryotes, and parthenogenetic or apomictic multi-celled organisms. DNA barcoding...
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