Higher-Level Taxonomy & Evolution Codexery

Eukaryote

Eukaryotes are organisms with a membrane-bound nucleus and organelles.

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Eukaryote

Gáspár Jékely · CC BY-SA 4.0

Eukaryotes are organisms whose cells contain a distinct nucleus enclosed by a membrane, along with other membrane-bound organelles.[1][2] They range from microscopic single cells to huge multicellular forms like the blue whale and coast redwood.[3] Prokaryotic cells have a volume roughly 10,000 times smaller than that of eukaryotic cells.[3]

Key facts and history

Many eukaryotes have mitochondria, organelles that produce ATP by oxidizing sugars or fats.[4] Mitochondria contain their own circular DNA, which originated from bacterial ancestors.[5] The last eukaryotic common ancestor (LECA) was likely a protist with a nucleus, flagellum, mitochondria, and sexual reproduction.[6] Fossils clearly related to modern eukaryotes appear around 1.2 billion years ago, with some possible older fossils dating to 1.8-1.6 billion years ago.[7][8]

Eukaryotes are set apart from prokaryotes by the presence of a nucleus enclosed within a membrane.[2] Inside the nucleus, the hereditary material is organized into several linear DNA strands termed chromosomes, which are condensed into chromatin with the help of histone proteins.[2][9] Chloroplasts, a type of plastid containing chlorophyll, are found in plants and various algae and are the sites of photosynthesis.[10] The last eukaryotic common ancestor (LECA) is hypothesized to have originated from a symbiotic event where an anaerobic archaean merged with an aerobic alphaproteobacterium.[11]

What the research sources say

A 2006 madsci.org article notes that Giardia was long thought to be a basal eukaryote from before mitochondrial endosymbiosis occurred.[12] The same source states that eukaryotes without obvious mitochondria are called amitochondrial organisms.[12] It further explains that all eukaryotes appear to have mitochondria or to be descended from an organism that had a functional mitochondrion.[12] According to one source, the initial eukaryotes that acquired endosymbionts were exceptionally successful, surpassing any nucleated organisms that lacked such symbionts in competition.[12]

References

  1. Wikipedia, "Eukaryote" (CC BY-SA 4.0) en.wikipedia.org
  2. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: Bonev, "Organization and function of the 3D genome", Nature Reviews Genetics, 14 October 2016, p. 661–678 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: Seenivasan, "Picomonas judraskeda Gen. Et Sp. Nov.: The First Identified Member of the Picozoa Phylum Nov., a Widespread Group of Picoeukaryotes, Formerly Known as 'Picobiliphytes'", PLOS ONE, 26 March 2013; Wood, "The Guinness Book of Animal Facts and Feats", Guinness World Records, 1983; "Sequoia sempervirens", The Gymnosperm Database, 2017; van den Hoek, "Algae An Introduction to Phycology", Cambridge University Press, 1995; "The eukaryotic tree of life from a global phylogenomic perspective", Cold Spring Harbor Perspectives in Biology, Ma en.wikipedia.org
  4. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: "Powerhouse of the Cell", Scientific American, July 1957, p. 131–144; "Fundamentals of Biochemistry", John Wiley and Sons, 2006, p. 547, 556; "Re: Are there eukaryotic cells without mitochondria?", madsci.org, 1 May 2006; Zick, "Cristae formation-linking ultrastructure and function of mitochondria.", Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, January 2009, p. 5–19 (we also read that source) en.wikipedia.org
  5. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: "Molecular Biology of the Gene", Benjamin Cummings, 1988, p. 1154 (original not read by us) en.wikipedia.org
  6. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: "Origin and Early Evolution of the Eukaryotic Cell", Annual Review of Microbiology, October 2021, p. 631–647; "Concepts of the last eukaryotic common ancestor", Nature Ecology & Evolution, March 2019, p. 338–344; "Predatory protists", Current Biology, May 2020, p. R510–R516; "A molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids", Nature Communications, March 2021; Koumandou, "Molecular paleontology and complexity in the last eukaryotic common ancestor", Critical Reviews in Biochemistry a en.wikipedia.org
  7. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: "The controversial "Cambrian" fossils of the Vindhyan are real but more than a billion years older", Proceedings of the National Academy of Sciences of the United States of America, May 2009, p. 7729–7734; Lechte, "Early fossil eukaryotes were benthic aerobes", Nature, 2026, p. 670–675 (original not read by us) en.wikipedia.org
  8. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: Fakhraee, "Earth's surface oxygenation and the rise of eukaryotic life: Relationships to the Lomagundi positive carbon isotope excursion revisited", Earth-Science Reviews, May 2023 (original not read by us) en.wikipedia.org
  9. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: O'Connor, "Chromosome Segregation: The Role of Centromeres", Nature Education, 2008 (original not read by us) en.wikipedia.org
  10. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: "The Structure and Function of Plastids", Springer Netherlands, 2006, p. 75–102; "Chloroplast DNA content in Dinophysis (Dinophyceae) from different cell cycle stages is consistent with kleptoplasty", Environ. Microbiol., September 2008, p. 2411–7; "Did some red alga-derived plastids evolve via kleptoplastidy? A hypothesis", Biological Reviews of the Cambridge Philosophical Society, February 2018, p. 201–222 (we also read that source) en.wikipedia.org
  11. Wikipedia, "Eukaryote" (CC BY-SA 4.0), which cites: "Origins and Evolution of Life: An astrobiological perspective", Cambridge University Press, 2011, p. 326–339 (original not read by us) en.wikipedia.org
  12. "Re: Are there eukaryotic cells without mitochondria?", madsci.org, 1 May 2006. facts only, no text reused. madsci.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Eukaryote (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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