Amoeba 1364 226153706 2008-07-17T01:46:12Z Ukexpat 70142 Reverted edits by [[Special:Contributions/60.241.82.45|60.241.82.45]] to last version by 213.16.241.12 (using [[WP:HG|Huggle]]) {{otheruses}} {{Taxobox| | name = ''Amoeba'' | color = khaki | image = Chaos diffluens.jpg | image_width = 250px | domain = [[Eukaryota]] | kingdom = [[Protista]] | class = Rhizopoda | order = [[Amoebida]] | familia = Amoebidae | genus = '''''Amoeba''''' | genus_authority = [[Bory de Saint-Vincent]], 1822 | subdivision_ranks = Species | subdivision = ''[[Amoeba proteus]]''<br> ''[[Amoeba dubia]]'' {{Expand-section|date=June 2008}} }} '''''Amoeba''''' (sometimes '''''amœba''''' or '''''ameba''''', plural '''''amoebae''''') is a [[genus]] of [[protozoa]] that moves by means of [[pseudopod]]s, and is well-known as a representative [[Microorganism|unicellular organism]]. The word '''amoeba''' or '''ameba''' is variously used to refer to it and its close relatives, now grouped as the [[Amoebozoa]], or to all protozoa that move using pseudopods, otherwise termed [[amoeboid]]s. ==History== The amoeba was first discovered by [[August Johann Rösel von Rosenhof]] in 1755.<ref>{{cite journal | last = Leidy | first = Joseph | title = Amoeba proteus | journal = The American Naturalist | volume = 12 | issue = 4 | year = 1878 | pages = 235–238 | url = http://links.jstor.org/sici?sici=0003-0147%28187804%2912%3A4%3C235%3AAP%3E2.0.CO%3B2-7 | accessdate = 2007-06-20 | doi = 10.1086/272082}}</ref> Early naturalists referred to ''Amoeba'' as the ''Proteus animalcule'' after the [[Greek mythology|Greek]] god [[Proteus]] who could change his shape. The name "amibe" was given to it by [[Bory de Saint-Vincent]]<ref>http://books.google.com/books?id=1I8DAAAAQAAJ&pg=PA158&lpg=PA158&dq=%22bory+de+saint+vincent+jean+baptiste+genevieve+marcellin%22+amibe&source=web&ots=SCcqmYPPSy&sig=vje4JuVmdQzWrFqpXTw2UjRsgx8#PPA5,M1</ref>, from the Greek ''amoibè'', meaning change.<ref name = EOS1>{{cite book | first = Kimberley | last = McGrath | coauthors = Blachford, Stacey (eds.) | title = Gale Encyclopedia of Science Vol. 1: Aardvark-Catalyst (2nd ed.) | year = 2001 | isbn = 078764370X | publisher = Gale Group}}</ref> ==Habitat and uses== ''Amoeba'' itself is found in decaying [[vegetation]], in [[Fresh water|fresh]] and [[Saline water|salt]] water, wet soil, and animals.<ref name = EOS1/> Due to the ease with which they may be obtained and kept alive, they are common objects of study as representative protozoa and to demonstrate cell structure and function. ==Anatomy== [[Image:Amoeba (PSF).png|thumb|250px|Anatomy of an amoeba]] The cell's [[organelle]]s and [[cytoplasm]] are enclosed by a [[cell membrane]], obtaining its food through [[phagocytosis]]. Amoebae have a single large tubular [[pseudopod]] at the [[Anatomical terms of location|anterior]] end, and several secondary ones branching to the sides. The most famous species, ''[[Amoeba proteus]]'', is 700-800 [[Micrometre|μm]] in length but the species ''[[Amoeba dubia]]'' is as large as a millimeter, and visible to the naked eye. Some ameobas have an appendage designed specifically for the phagocytosis of silicone{{Fact|date=May 2008}} . Its most recognizable features include one or more [[cell nuclei|nuclei]] and a simple contractile [[vacuole]] to maintain [[osmosis|osmotic equilibrium]]. Food enveloped by the amoeba is stored and digested in vacuoles. Amoebae reproduce via [[binary fission]]. In cases where the amoeba are forcibly divided, the portion that retains the nucleus will survive and form a new cell and cytoplasm, while the other portion dies. Amoebas also have no definite shape.<ref name = SC>{{cite web | url = http://www.scienceclarified.com/Al-As/Amoeba.html | language = english | format = html | publisher = Scienceclarified.com | title = Amoeba | == Reaction to stimuli == === Hypertonic and hypotonic solutions === Like most cells, amoebae are adversely affected by excessive [[Osmosis|osmotic pressure]] caused by extremely saline or dilute water. Amoebae will prevent the influx of salt in saline water, resulting in a net loss of water as the cell becomes [[isotonic]] with the environment, causing the cell to shrink. Placed into [[fresh water]], amoebae will also attempt to match the concentration of the surrounding water, causing the cell to swell and sometimes burst.<ref name=Patterson1981>{{cite journal | author = Patterson, D.J. | year = 1981 | title = Contractile vacuole complex behaviour as a diagnostic character for free living amoebae | journal = Protistologica | volume = 17 | pages = 243–248}}</ref> Adjusting the tonicity of the cytoplasm can also damage the digestive enzymes used in phagocytosis, allowing the amoeba to ingest food but not extract energy, resulting in death.<ref name = EOS1/> === Amoebic cysts === {{main|Microbial cyst}} In environments which are potentially lethal to the cell, an amoeba may become dormant by forming itself into a ball and secreting a protective membrane to become a [[microbial cyst]]. The cell remains in this state until it encounters more favourable conditions.<ref name = SC/> While in cyst form the amoeba will not replicate and may die if unable to emerge for a lengthy period of time. === Marine amoeba === Marine amoeba lack contractile vacuoles and their [[enzyme]]s and organelles are not damaged by the salt water found in seas, oceans, salt swamps, salty rivers and ponds. ==In popular culture== {{Trivia|date=July 2008}} <!-- Please add all the meanings which are not directly related to the biological creature to [[Amoeba (disambiguation)]]. --> *[[Tom Robbins]] states in the [[preface]] to his 1976 novel ''[[Even Cowgirls Get the Blues]]'' that amoebas are [[Cool (aesthetic)|cool]] because they [[reproduce]] by [[binary fission]], so the first amoeba is still alive to this day. The first sentence of the book is "Amoebae have no fossils." * In the 1984 computer game [[Boulder Dash]], Rockford, the main character, interacts frequently with a constantly-growing green amoeba. * The contemporary British Poet, [[John Hegley]], has a poem entitled ''Amoeba''. * [[The Adolescents]] have a song titled "Amoeba" * [[The Powerpuff Girls]] and [[Demashita! Powerpuff Girls Z]] have a trio of villains called The Amoeba Boys, who are shown to be lacking in their capacity for true villainous activity (as in one episode, where they steal an orange from a street vendor, and then give it back) compared with world-domination-centered villains such as Mojo Jojo. This seems to be explained by their lack of brain (being single-celled organisms). * The 48th produced episode of the classic [[Star Trek: The Original Series|Star Trek]] series ([[The Immunity Syndrome (TOS episode)|The Immunity Syndrome]]) featured an 11,000-mile (~17 700 km) wide amoeba threatening not only the life of Captain Kirk and his crew, but all life throughout the galaxy. * In the fourth installment of [[The Legend of Zelda]] ([[Ocarina of Time]]), the dungeon boss of the Water Temple is a giant Amoeba that fuses with the water around it. * Jon Scieszka's book, ''[[Science Verse]]'', had a poem called ''Amoeba where are you aneba" * In the second epidode of [[Futurama]], Bender says to Fry that he hasn't "touched his amoeba" in a sushi like restaurant. The amoeba is depicted as a large, green, jelly-like blob. ==References== {{Reflist}} ==External links== * [http://tolweb.org/notes/?note_id=51 Amoebae: Protists Which Move and Feed Using Pseudopodia, David Patterson (Tree of Life)] * [http://wikibooks.org/wiki/Biology_Cell_biology_Introduction_Cell_size Wikibooks: compare size of cells] * [http://www.bairbrepaws.com/psneeley/FwrPLA.htm Joseph Leidy's Amoeba Plates] [[Category:Protista]] [[Category:Amoeboids]] [[Category:Amoebozoa]] [[ar:أميبا (كائن دقيق)]] [[bs:Amebe]] [[bg:Амеба]] [[da:Amøbe]] [[de:Amöbe]] [[el:Αμοιβάδα]] [[et:Amööb]] [[es:Ameba]] [[fr:Amibe]] [[ko:아메바]] [[hi:अमीबा]] [[it:Amoeba]] [[he:אמבה]] [[lt:Amebos]] [[nl:Amoebe]] [[ja:アメーバ]] [[no:Amøbe]] [[nn:Amøbe]] [[pl:Ameby]] [[sq:Ameba]] [[sr:Амеба]] [[fi:Amebat]] [[th:อะมีบา]] [[uk:Амеба]] [[zh:變形蟲]]