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Protist
Fossil range: Neoproterozoic - Recent
Scientific classification
Domain: Eukarya
Kingdom: Protista*
Haeckel, 1866
Typical phyla
.Protists (pronounced /ˈproʊtɨst/) are a diverse group of eukaryotic microorganisms.^ Because the protists as a whole are paraphyletic, such systems often split up or abandon the kingdom, instead treating the protist groups as separate lines of eukaryotes.
  • Protist - Paleontology Wiki 1 February 2010 3:45 UTC paleontology.wikia.com [Source type: FILTERED WITH BAYES]

^ A portal into the various groups of protists (and other eukaryotes) with many illustrations in color.
  • The Protists 1 February 2010 3:45 UTC users.rcn.com [Source type: FILTERED WITH BAYES]

^ Clear Turn Off Turn On The extent of protist diversity: insights from molecular ecology of freshwater eukaryotes The extent of protist diversity: insights from molecular ecology of freshwater eukaryotes Your browsing activity is empty.
  • The extent of protist diversity: insights from molecular ecology of freshwater eukaryotes 1 February 2010 3:45 UTC www.ncbi.nlm.nih.gov [Source type: Academic]

.Historically, protists were treated as the kingdom Protista but this group is no longer recognized in modern taxonomy.^ Because the protists as a whole are paraphyletic, such systems often split up or abandon the kingdom, instead treating the protist groups as separate lines of eukaryotes.
  • Protist - Hwiki 1 February 2010 3:45 UTC hwiki.fzk.de [Source type: FILTERED WITH BAYES]

^ Introduction Unicellular eukaryotes belong to the kingdom Protista, and are often referred to as protists or protozoans.
  • Sample Descriptive Lab Report 1 February 2010 3:45 UTC www.ncsu.edu [Source type: FILTERED WITH BAYES]

^ The tendency was to treat Kingdom Protista as the taxonomic home for all eukaryotes that did not fit comfortably into the definitions of plants, fungi, and animals.

[1] .Instead, it is "better regarded as a loose grouping of 30 or 40 disparate phyla with diverse combinations of trophic modes, mechanisms of motility, cell coverings and life cycles."^ These taxonomic transfers were based mainly on comparisons of cell structure and details of life cycles.

^ See Figure 28.30, The life cycle of a cellular slime mold ( Dictyostelium ) .

^ Obliged to live within the cells of its host, it has lost the genes for many important functions (e.g., the citric acid cycle ) depending instead on its host.
  • The Protists 1 February 2010 3:45 UTC users.rcn.com [Source type: FILTERED WITH BAYES]

[2]
.The protists do not have much in common besides a relatively simple organization[3] — either they are unicellular, or they are multicellular without specialized tissues.^ All are multicellular although without much specialization of cell types.
  • The Protists 1 February 2010 3:45 UTC users.rcn.com [Source type: FILTERED WITH BAYES]

^ The protists are a paraphyletic grade, rather than a natural ( monophyletic ) group, and do not have much in common besides a relatively simple organization (unicellular, or multicellular without highly specialized tissues).
  • Protist - Paleontology Wiki 1 February 2010 3:45 UTC paleontology.wikia.com [Source type: FILTERED WITH BAYES]
  • Protist - Hwiki 1 February 2010 3:45 UTC hwiki.fzk.de [Source type: FILTERED WITH BAYES]

^ Generally, protists are "unicellular eukaryotes that either exist as independent cells, or if they occur in colonies, do not show differentiation into tissues."
  • Protozoans Against Intelligent Design - Science and Technology - Shroomery Message Board 1 February 2010 3:45 UTC www.shroomery.org [Source type: FILTERED WITH BAYES]

.This simple cellular organization distinguishes the protists from other eukaryotes, such as fungi, animals and plants.^ Protists gave rise to all other plants and animals.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ Protists are mainly defined by what they are not - they are not bacteria or fungi, they are not plants or animals.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ Other protists are all unicellular heterotrophic eukaryotes (except for Fungi) .
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

.The term protista was first used by Ernst Haeckel in 1866.^ The term was first suggested in 1866 by Ernst Haeckel .
  • protist (biology) -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

.Protists were traditionally subdivided into several groups based on similarities to the "higher" kingdoms: the one-celled animal-like protozoa, the plant-like protophyta (mostly one-celled algae), and the fungus-like slime molds and water molds.^ Plasmodium Plasmodium is a parasitic animal-like protist.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

^ Two examples of the fungus-like protists are water molds and slime molds.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

^ Brown algae is a plant-like protist found in cool temperature marine waters.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

.Because these groups often overlap, they have been replaced by phylogenetic-based classifications.^ Almost all of them have chlorophyll A, most have chlorophyll C, but only a few have chlorophyll B. They also have a variety of carotenoids and other pigments, and frequently they are grouped into Divisions based on similarities in pigments.

^ Q) Are "phylogenetic-based classifications" changing the look of the "tree of life" I learned about in grade ten biology?
  • The Tree of Life: Confronting Intelligent Design arguments directly in the scientific literature 1 February 2010 3:45 UTC phylogenomics.blogspot.com [Source type: Academic]

^ All of the characteristics that this group shares are primitive traits, a perilous thing to base any classification on, because convergent evolution may be responsible for these superficial similarities.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

.However, they are still useful as informal names for describing the morphology and ecology of protists.^ As the early descriptions were based on light microscopical observation, they used to include several protist genera of uncertain affinity, such as Phyllomitus spp.
  • Katablepharids 1 February 2010 3:45 UTC tolweb.org [Source type: Academic]

^ For instance, in addition to administering the polypeptides to a patient, animal or plant, they may be used to coat surfaces and objects to prevent or treat fungal and/or a protist contamination.
  • Treatment of Fungal and/or Protist Infections - Patent application 1 February 2010 3:45 UTC www.faqs.org [Source type: Reference]

^ The FISH using the group-specific probe also detected the symbionts of the same morphology from almost all the cells of the protist species.
  • BioMed Central | Full text | Complex coevolutionary history of symbiotic Bacteroidales bacteria of various protists in the gut of termites 1 February 2010 3:45 UTC www.biomedcentral.com [Source type: Academic]

.Protists live in almost any environment that contains liquid water.^ Water molds are fungus-like protists that live in moist environments.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

^ Amoebas are single celled animal-like protists that live in moist soil, freshwater, and salt water.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

^ Jars of pond water that contain some decaying vegetation and kept at room temperature for several days will often teem with populations of protists.
  • BioMEDIA ASSOCIATES 1 February 2010 3:45 UTC ebiomedia.com [Source type: FILTERED WITH BAYES]

.Many protists, such as the algae, are photosynthetic and are vital primary producers in ecosystems, particularly in the ocean as part of the plankton.^ In addition, many protists harbour prokaryotes or eukaryotes (such as those that gave rise to secondary and tertiary plastids [ 7 ]) as endosymbionts.
  • BioMed Central | Full text | Evolution of four gene families with patchy phylogenetic distributions: influx of genes into protist genomes 1 February 2010 3:45 UTC www.biomedcentral.com [Source type: Academic]

^ It is thought that through evolution they have gained the ability to function as primary producers by "capturing" and using chloroplasts from other algae.

^ Even among the photosynthetic protists, different combinations of photopigments, various schemes for storing food, and a variety of reproduction schemes makes it unlikely that many of these are related.
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.Other protists, such as the Kinetoplastids and Apicomplexa, are responsible for a range of serious human diseases, such as malaria and sleeping sickness.^ Animal-like protists are responsible for diseases such as malaria, amoebic dysentery, toxoplasmosis, African Sleeping Sickness and Giardiasis in humans.
  • BioEd Online Slides: "unicellular", bacteria, unicellular, protist 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]
  • BioEd Online Slides: "protist", protist, hand lens, cells, protozoan 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]

^ Malaria has probably caused more human deaths than any other infectious disease; even today it is estimated to kill a million people a year in the sub-Saharan Africa.
  • The Protists 1 February 2010 3:45 UTC users.rcn.com [Source type: FILTERED WITH BAYES]

^ Another blood parasite, Trypanosoma (shown live in a drop of blood) produces an often fatal disease--sleeping sickness.
  • BioMEDIA ASSOCIATES 1 February 2010 3:45 UTC ebiomedia.com [Source type: FILTERED WITH BAYES]

Contents

Classification

Historical classifications

.The first division of the protists from other organisms came in the 1830s, when the German biologist Georg A. Goldfuss introduced the word protozoa to refer to organisms such as ciliates and corals.^ Protists belong to the Kingdom Protista, which include mostly unicellular organisms that do not fit into the other kingdoms.
  • Saugerties Jr High School | Van Voorhis, Ms.-Science 1 February 2010 3:45 UTC www.saugerties.k12.ny.us [Source type: FILTERED WITH BAYES]

^ In other words, these species are more closely related to each other than to any organism that lacks a flagellum.
  • Gonzology: Protist Phylogeny 1 February 2010 3:45 UTC gonzology.gonzaga.edu [Source type: FILTERED WITH BAYES]

^ Q. - Why do biologist place suctorians (organisms without cilia) on the ciliate line of evolution?
  • BioMEDIA ASSOCIATES 1 February 2010 3:45 UTC ebiomedia.com [Source type: FILTERED WITH BAYES]

[4] .This group was expanded in 1845 to include all "unicellular animals", such as Foraminifera and amoebae.^ The amoebas are all unicellular.
  • Gonzology: Protist Identification 1 February 2010 3:45 UTC gonzology.gonzaga.edu [Source type: FILTERED WITH BAYES]

^ The amoebae in the Unikont group are more closely related to animals than they are to other so-called amoebae in the other groups, such as...RHIZARIA, a group of mostly amoebae that include the exquisitely beautiful Radiolarians, Foraminiferans (which Haeckel loved and illustrated profusely), various plant parasites, and a whole host of other interesting unicellular creatures.
  • Ernst Haeckel: The Intersection of Art and Science Boing Boing 1 February 2010 3:45 UTC www.boingboing.net [Source type: General]

^ More recently, the concept of protists was expanded to include certain multicellular organisms such as kelp (Copeland, 1956).
  • BioEd Online Slides: "unicellular", bacteria, unicellular, protist 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]
  • BioEd Online Slides: "protist", protist, hand lens, cells, protozoan 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]
  • K8 Science Slides: "eukaryote", microbes, yeast, unicellular, protist 1 February 2010 3:45 UTC www.k8science.org [Source type: Academic]

.The formal taxonomic category Protoctista was first proposed in the early 1860s by John Hogg, who argued that the protists should include what he saw as primitive unicellular forms of both plants and animals.^ It does not include Plants, Animals, or Fungi.
  • BIO102, Chapt 28 1 February 2010 3:45 UTC www.biol.sc.edu [Source type: Academic]

^ Protists belong to the Kingdom Protista, which include mostly unicellular organisms that do not fit into the other kingdoms.
  • Saugerties Jr High School | Van Voorhis, Ms.-Science 1 February 2010 3:45 UTC www.saugerties.k12.ny.us [Source type: FILTERED WITH BAYES]

^ "Protist" refers to simple eukaryotic organisms, and includes the unicellular eukaryotes as well the uni-cellular and multi-cellular algae.
  • BIO102, Chapt 28 1 February 2010 3:45 UTC www.biol.sc.edu [Source type: Academic]

.He defined the Protoctista as a "fourth kingdom of nature", in addition to the then-traditional kingdoms of plants, animals and minerals.^ The semiconstrained tree was developed by using the distance tree to define the following subtrees: the spirochetes, the γ- and β-Proteobacteria, the non-Rickettsiales α-Protebacteria and a mitochondrial cpn60 subtree of animals, fungi, and plants.
  • A possible mitochondrial gene in the early-branching amitochondriate protist Trichomonas vaginalis — PNAS 1 February 2010 3:45 UTC www.pnas.org [Source type: Academic]

^ The eukaryotes represent a monophyletic domain , one made up of the prot i sta , the fungi , the animals , and the plants (as named according to the five-kingdom system 5ks ) .

^ Next to the Chromacea come the Bacteria, which have been evolved from them by the remarkable change in nutrition which gives us the simple explanation of the differentiation of plant and animal in the protist kingdom.
  • Our Protist Ancestors 1 February 2010 3:45 UTC englishatheist.org [Source type: Original source]

[4] .The kingdom of minerals was later removed from taxonomy by Ernst Haeckel, leaving plants, animals, and the protists as a “kingdom of primitive forms”.^ In many ways fungi are more closely related to animals than to plants , and they have been thought to share a common protist ancestor with animals.
  • SgForums :: Singapore's Online Community - Why fern is an animal? HELP!!! 1 February 2010 3:45 UTC www.sgforums.com [Source type: FILTERED WITH BAYES]

^ Some protists are considered the ancestors of multicellular plants, animals, and fungi.
  • protist (biology) -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Sometime in the last billion years, multicellular eukaryotic plants and then primitive animal forms (e.g., protozoa) that have evolved into today's varieties (metazoa).
  • Remote Sensing Tutorial Page A-12 1 February 2010 3:45 UTC www.fas.org [Source type: FILTERED WITH BAYES]

[5]
.Herbert Copeland resurrected Hogg's label almost a century later, arguing that "Protoctista" literally meant "first established beings", Copeland complained that Haeckel's term protista included anucleated microbes such as bacteria.^ The term was first suggested in 1866 by Ernst Haeckel .
  • protist (biology) -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ So, as described above, almost certainly the first living bodies were microscopic in size, being single-celled.
  • Remote Sensing Tutorial Page A-12 1 February 2010 3:45 UTC www.fas.org [Source type: FILTERED WITH BAYES]

Copeland's use of the term protoctista did not. .In contrast, Copeland's term included nucleated eukaryotes such as diatoms, green algae and fungi.^ Plants , including the green algae ( Chlorophyta ) are described in a separate page.
  • The Protists 1 February 2010 3:45 UTC users.rcn.com [Source type: FILTERED WITH BAYES]

^ In terms of conventional classifications of the lower eukaryotes but considering the system used in this article, the major taxa treated here as protists include the algae , the protozoa, and the so-called lower, or zoosporic (motile), fungi.
  • protist (biology) -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ However, such organisms as Brown, Red and Green algae are not single celled, and have distinct tissues and reproductive organs.
  • BIO102, Chapt 28 1 February 2010 3:45 UTC www.biol.sc.edu [Source type: Academic]

[6] .This classification was the basis for Whittaker's later definition of Fungi, Animalia, Plantae and Protista as the four kingdoms of life.^ Kingdom Monera (bacteria and viruses), and the Kingdom Fungi, and also the Kingdom Protista.
  • Treatment of Fungal and/or Protist Infections - Patent application 1 February 2010 3:45 UTC www.faqs.org [Source type: Reference]

^ Members of the microbial kingdom Protista originally were defined by structure (mainly unicellular eukaryotes) and by the difficulty to classify them as either plant, fungi or animal.
  • BioEd Online Slides: "unicellular", bacteria, unicellular, protist 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]
  • BioEd Online Slides: "protist", protist, hand lens, cells, protozoan 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]

^ In 1969, Robert Whittaker proposed a five-kingdom system consisting of monerans, protists, fungi, plants and animals.
  • BioEd Online Slides: "protist", protist, hand lens, cells, protozoan 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]

[7] .The kingdom Protista was later modified to separate prokaryotes into the separate kingdom of Monera, leaving the protists as a group of eukaryotic microorganisms.^ Then attempt to group the phyla into kingdoms.
  • http://www.bio.ilstu.edu/Armstrong/biolab/cellbio/protist1.htm 1 February 2010 3:45 UTC www.bio.ilstu.edu [Source type: FILTERED WITH BAYES]

^ A portal into the various groups of protists (and other eukaryotes) with many illustrations in color.
  • The Protists 1 February 2010 3:45 UTC users.rcn.com [Source type: FILTERED WITH BAYES]

^ In addition, many protists harbour prokaryotes or eukaryotes (such as those that gave rise to secondary and tertiary plastids [ 7 ]) as endosymbionts.
  • BioMed Central | Full text | Evolution of four gene families with patchy phylogenetic distributions: influx of genes into protist genomes 1 February 2010 3:45 UTC www.biomedcentral.com [Source type: Academic]

[8] .These five kingdoms remained the accepted classification until the development of molecular phylogenetics in the late 20th century, when it became apparent that neither protists or monera were single groups of related organisms (they were not monophyletic groups).^ In the Five Kingdom system of classification, all prokaryotes are assigned to the Kingdom Monera.
  • BioEd Online Slides: "unicellular", bacteria, unicellular, protist 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]

^ Chart includes locomotion, nutrition, group classification, reproduction along with links to "Protist Game", "Protist Hangman".

^ In many ways fungi are more closely related to animals than to plants , and they have been thought to share a common protist ancestor with animals.
  • SgForums :: Singapore's Online Community - Why fern is an animal? HELP!!! 1 February 2010 3:45 UTC www.sgforums.com [Source type: FILTERED WITH BAYES]

Modern classifications

.Currently, the term protist is used to refer to unicellular eukaryotes that either exist as independent cells, or if they occur in colonies, do not show differentiation into tissues.^ They can be either unicellular or multicellular, and in this group we find the first inkling of what is to come in evolutionary history, the union of eukaryotic cells into a colonial organism, where various cell types perform certain tasks, communicate with one another, and together function like a multicellular organism.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ Samuel Arbesman designed the “Milky Way Transit Authority” using only the tube map as a working model… Protozoans Against Intelligent Design — The Journal of Eukaryotic Microbiology has just published a very nice paper showing how the details of protist evolution “dispel the myths of intelligent design.” Generally, protists are “unicellular eukaryotes that either exist as independent cells, or if they occur in colonies, do not show differentiation into tissues.” Think amoebae or foraminifera… .

^ Protists belong to the Kingdom Protista, which include mostly unicellular organisms that do not fit into the other kingdoms.
  • Saugerties Jr High School | Van Voorhis, Ms.-Science 1 February 2010 3:45 UTC www.saugerties.k12.ny.us [Source type: FILTERED WITH BAYES]

[9] .The term protozoa is used to refer to heterotrophic species of protists that do not form filaments.^ Most species are multicellular often with interwoven fibers forming filaments, which are delicate and feathering .
  • Kingdom Protista - The Algae 1 February 2010 3:45 UTC www.hutchcc.edu [Source type: FILTERED WITH BAYES]

^ The term "yeast" is used to described any single-celled fungus species, including Baker's yeast ( Saccharomyces cerevisiae ).
  • K8 Science Slides: "eukaryote", microbes, yeast, unicellular, protist 1 February 2010 3:45 UTC www.k8science.org [Source type: Academic]

^ The cells of the protist species that stably harbored Bacteroidales symbionts were physically isolated and used for PCR amplification of bacterial 16S rRNA gene.
  • BioMed Central | Full text | Complex coevolutionary history of symbiotic Bacteroidales bacteria of various protists in the gut of termites 1 February 2010 3:45 UTC www.biomedcentral.com [Source type: Academic]

.These terms are not used in current taxonomy, and are retained only as convenient ways to refer to these organisms.^ We also combined these results with the information from published genomes and mapped the occurrences of the genes onto the current hypothesis of organismal relationships among eukaryotes (Figure 1 ) [ 29 - 31 ].
  • BioMed Central | Full text | Evolution of four gene families with patchy phylogenetic distributions: influx of genes into protist genomes 1 February 2010 3:45 UTC www.biomedcentral.com [Source type: Academic]

^ It is not inappropriate to use, so long as the user realizes it loosly refers to those eukaryotes which are simple in body plan, to the point of usually being single celled organisms.
  • BIO102, Chapt 28 1 February 2010 3:45 UTC www.biol.sc.edu [Source type: Academic]

^ These protozoans are solitary, fresh water organisms and use cilia to move.

The taxonomy of protists is still changing. .Newer classifications attempt to present monophyletic groups based on ultrastructure, biochemistry, and genetics.^ All of the characteristics that this group shares are primitive traits, a perilous thing to base any classification on, because convergent evolution may be responsible for these superficial similarities.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ Taxonomy of the group is based on the type of pseudopodia and test (shell), if present.
  • New Page 0 1 February 2010 3:45 UTC cas.bellarmine.edu [Source type: FILTERED WITH BAYES]

^ Classification systems based on five or even eight kingdoms place polyphyletic groups of protists in the same kingdom.
  • Gonzology: Protist Identification 1 February 2010 3:45 UTC gonzology.gonzaga.edu [Source type: FILTERED WITH BAYES]

.Because the protists as a whole are paraphyletic, such systems often split up or abandon the kingdom, instead treating the protist groups as separate lines of eukaryotes.^ The tendency was to treat Kingdom Protista as the taxonomic home for all eukaryotes that did not fit comfortably into the definitions of plants, fungi, and animals.

^ A third Domain, Eukarya, consists of all Eukaryotic organisms, such as plants, animals, fungi and protists.
  • BioEd Online Slides: "unicellular", bacteria, unicellular, protist 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]

^ Altogether, these observations suggest that an important fraction of the eukaryotic diversity is still awaiting discovery, even for very well known groups such as the ciliates.
  • The extent of protist diversity: insights from molecular ecology of freshwater eukaryotes 1 February 2010 3:45 UTC www.ncbi.nlm.nih.gov [Source type: Academic]

.The recent scheme by Adl et al. (2005)[9] is an example that does not bother with formal ranks (phylum, class, etc.^ For example, Azuma et al.
  • Treatment of Fungal and/or Protist Infections - Patent application 1 February 2010 3:45 UTC www.faqs.org [Source type: Reference]

^ Recent work suggests that green and red algae are more closely allied with land plants, and that slime molds are more closely allied to animals (Baldauf, et al.
  • BioEd Online Slides: "unicellular", bacteria, unicellular, protist 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]
  • BioEd Online Slides: "protist", protist, hand lens, cells, protozoan 1 February 2010 3:45 UTC www.bioedonline.org [Source type: Academic]
  • K8 Science Slides: "eukaryote", microbes, yeast, unicellular, protist 1 February 2010 3:45 UTC www.k8science.org [Source type: Academic]

^ Recent works have shown that morphologically well defined species may have highly divergent SSU rDNA sequences that do not branch within the expected ciliate classes ( Johnson et al .
  • The extent of protist diversity: insights from molecular ecology of freshwater eukaryotes 1 February 2010 3:45 UTC www.ncbi.nlm.nih.gov [Source type: Academic]

) and instead lists organisms in hierarchical lists. .This is intended to make the classification more stable in the long term and easier to update.^ About Us Privacy Policy Terms of Use RSS Feeds E-mail Updates Contact Us Advertise with Us Games MORE...
  • protist (biology) -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]
  • protist (biology) :: Reproduction and life cycles -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

.Some of the main groups of protists, which may be treated as phyla, are listed in the taxobox at right.^ Some protists are heterotrophs , a group of phyla called the protozoa.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ Some protists are autotrophs , a photosynthetic group of phyla referred to as the algae.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ Polypeptides according to the invention may be used to treat fungal and/or protist infections as a monotherapy (i.e.
  • Treatment of Fungal and/or Protist Infections - Patent application 1 February 2010 3:45 UTC www.faqs.org [Source type: Reference]

[10] .Many are thought to be monophyletic, though there is still uncertainty.^ No one even knows how many species there are, though estimates range between 65,000 to 200,000.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ That means that even though there are many cells in one organism, the cells are all of the same type, or almost all of the same type.
  • Protist Lab 1 February 2010 3:45 UTC faculty.stcc.edu [Source type: FILTERED WITH BAYES]

For instance, the excavates are probably not monophyletic and the chromalveolates are probably only monophyletic if the haptophytes and cryptomonads are excluded.[11]

Metabolism

.Nutrition in some different types of protists is variable.^ Contains pictures and brief descriptions of different types of protists.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

^ Contains information and charts about plant-like protests, has links to different types of plant-like protists.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

^ Todays euglenids are modern representative of an ancient line of life, so different from other protists that some biologists have suggested placing them in a kingdom of their own.
  • BioMEDIA ASSOCIATES 1 February 2010 3:45 UTC ebiomedia.com [Source type: FILTERED WITH BAYES]

.In flagellates, for example, filter feeding may sometimes occur where the flagella find the prey.^ The polypeptides or derivatives may be used to treat any mammal, for example, human, livestock, pets, to prevent infection from occurring.
  • Treatment of Fungal and/or Protist Infections - Patent application 1 February 2010 3:45 UTC www.faqs.org [Source type: Reference]

.Other protists can engulf bacteria and digest them internally, by extending their cell membrane around the food material to form a food vacuole.^ Single celled bacteria and protists are immortal.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ The bacteria selected are engulfed in a food vacuole that pinches off and circulates through the cell while the bacteria digest.
  • BioMEDIA ASSOCIATES 1 February 2010 3:45 UTC ebiomedia.com [Source type: FILTERED WITH BAYES]

^ With plenty of organisms to examine one can observe: How Paramecium feeds on bacteria by phagocytosis and digests them in food vacuoles.
  • BioMEDIA ASSOCIATES 1 February 2010 3:45 UTC ebiomedia.com [Source type: FILTERED WITH BAYES]

.This is then taken into the cell via endocytosis (usually phagocytosis; sometimes pinocytosis).^ Most ciliates engulf their food by phagocytosis, a process of surrounding the food with plasma membrane as it is taken into the cell.
  • BioMEDIA ASSOCIATES 1 February 2010 3:45 UTC ebiomedia.com [Source type: FILTERED WITH BAYES]

^ Desmids are typically one-celled, though sometimes filamentous or colonial, and are divided symmetrically into semicells connected at a central point.
  • Molecular Expressions Digital Video Gallery: Pond Life 1 February 2010 3:45 UTC micro.magnet.fsu.edu [Source type: FILTERED WITH BAYES]

Nutritional types in protist metabolism
Nutritional type Source of energy Source of carbon Examples
 Phototrophs   Sunlight   Organic compounds or carbon fixation  Algae, Dinoflagellates or Euglena 
 Organotrophs  Organic compounds   Organic compounds   Apicomplexa, Trypanosomes or Amoebae 

Reproduction

.Some protists reproduce sexually, while others reproduce asexually.^ Protists reproduce asexually by binary fission, and a few species are capable of sexual reproduction.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ Some multicellular algal protists reproduce via asexual spores, structures that are themselves often produced by a series of rapid fissions.
  • protist (biology) :: Reproduction and life cycles -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ The following are some people associated with "protist" Charles Atwood Kofoid (American zoologist) Herbert Spencer Jennings (American zoologist) Other .
  • protist (biology) -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]
  • protist (biology) :: Reproduction and life cycles -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

.Some species, for example Plasmodium falciparum, have extremely complex life cycles that involve multiple forms of the organism, some of which reproduce sexually and others asexually.^ Many have very complex life cycles.
  • Kingdom Protist Information 1 February 2010 3:45 UTC pangea.tec.selu.edu [Source type: FILTERED WITH BAYES]

^ Below is the life cycle of Plasmodium.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

^ Algal life cycles, examples .

[12] .However, it is unclear how frequently sexual reproduction causes genetic exchange between different strains of Plasmodium in nature and most populations of parasitic protists may be clonal lines that rarely exchange genes with other members of their species.^ In fact, sexual reproduction —that is, the union of one male and one female gamete (syngamy)—is the most common sexual phenomenon and occurs quite widely among the protists—for example, among various flagellate and sarcodine groups and among many parasitic phyla ( e.g., in Plasmodium, a malaria-causing organism).
  • protist (biology) :: Reproduction and life cycles -- Britannica Online Encyclopedia 1 February 2010 3:45 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Most species that belong to this phylum are parasitic, some of which parasitize animals and humans.
  • Molecular Expressions Digital Video Gallery: Pond Life 1 February 2010 3:45 UTC micro.magnet.fsu.edu [Source type: FILTERED WITH BAYES]

^ The probe Bactd-937 for most Bacteroidales members [ 23 ] was used for the initial survey of protist-associated symbionts.
  • BioMed Central | Full text | Complex coevolutionary history of symbiotic Bacteroidales bacteria of various protists in the gut of termites 1 February 2010 3:45 UTC www.biomedcentral.com [Source type: Academic]

[13]

Role as pathogens

.Some protists are significant pathogens of both animals and plants.^ Some parasitize plants, invertebrate animals and other protists.
  • Cercozoa 1 February 2010 3:45 UTC tol.tolweb.org [Source type: FILTERED WITH BAYES]

^ In many ways fungi are more closely related to animals than to plants , and they have been thought to share a common protist ancestor with animals.
  • SgForums :: Singapore's Online Community - Why fern is an animal? HELP!!! 1 February 2010 3:45 UTC www.sgforums.com [Source type: FILTERED WITH BAYES]

^ Next to the Chromacea come the Bacteria, which have been evolved from them by the remarkable change in nutrition which gives us the simple explanation of the differentiation of plant and animal in the protist kingdom.
  • Our Protist Ancestors 1 February 2010 3:45 UTC englishatheist.org [Source type: Original source]

.For example Plasmodium falciparum which causes malaria in humans and Phytophthora infestans which causes potato blight.^ The genus Plasmodium causes malaria , one of the greatest scourges of humans.
  • The Protists 1 February 2010 3:45 UTC users.rcn.com [Source type: FILTERED WITH BAYES]

^ Phytophthora infestans , the cause of the "late blight" of potatoes.
  • The Protists 1 February 2010 3:45 UTC users.rcn.com [Source type: FILTERED WITH BAYES]

^ For example, Ridomil Gold MZ may be applied to foliage of potato plants to control late blight caused by Phytophthora infestans.
  • Treatment of Fungal and/or Protist Infections - Patent application 1 February 2010 3:45 UTC www.faqs.org [Source type: Reference]

.A more thorough understanding of protist biology may allow these diseases to be treated more effectively.^ Many of these protists are disease causing.
  • Protista Group 1 February 2010 3:45 UTC students.ncwc.edu [Source type: FILTERED WITH BAYES]

^ The phylogeny of the Bacteroidales symbionts were inferred to understand the relationships to the host protist phylogeny, the connection with their morphology, the extent of their specificity, and the evolutionary process of these impressive symbiotic associations.
  • BioMed Central | Full text | Complex coevolutionary history of symbiotic Bacteroidales bacteria of various protists in the gut of termites 1 February 2010 3:45 UTC www.biomedcentral.com [Source type: Academic]

^ Polypeptides according to the invention may be used to treat fungal and/or protist infections as a monotherapy (i.e.
  • Treatment of Fungal and/or Protist Infections - Patent application 1 February 2010 3:45 UTC www.faqs.org [Source type: Reference]

See also

References

  1. ^ Simonite T (November 2005). "Protists push animals aside in rule revamp". Nature 438 (7064): 8–9. doi:10.1038/438008b. PMID 16267517. 
  2. ^ Harper, David; Benton, Michael (2009). Introduction to Paleobiology and the Fossil Record. Wiley-Blackwell. pp. 207. ISBN 1-4051-4157-3. 
  3. ^ "Systematics of the Eukaryota". http://www.ucmp.berkeley.edu/alllife/eukaryotasy.html. Retrieved 2009-05-31. 
  4. ^ a b Scamardella, J. M. (1999). "Not plants or animals: a brief history of the origin of Kingdoms Protozoa, Protista and Protoctista". International Microbiology 2: 207–221. http://www.im.microbios.org/08december99/03%20Scamardella.pdf. 
  5. ^ Rothschild LJ (1989). "Protozoa, Protista, Protoctista: what's in a name?". J Hist Biol 22 (2): 277–305. doi:10.1007/BF00139515. PMID 11542176. http://www.springerlink.com/index/LW54T61737212643.pdf. 
  6. ^ Copeland, H. F. (1938). "The Kingdoms of Organisms". Quarterly Review of Biology 13 (4): 383. doi:10.1086/394568. http://links.jstor.org/sici?sici=0033-5770(193812)13%3A4%3C383%3ATKOO%3E2.0.CO%3B2-K. 
  7. ^ Whittaker, R. H. (1959). "On the Broad Classification of Organisms". Quarterly Review of Biology 34 (3): 210. doi:10.1086/402733. http://links.jstor.org/sici?sici=0033-5770(195909)34%3A3%3C210%3AOTBCOO%3E2.0.CO%3B2-J. 
  8. ^ Whittaker RH (January 1969). "New concepts of kingdoms or organisms. Evolutionary relations are better represented by new classifications than by the traditional two kingdoms". Science (journal) 163 (863): 150–60. doi:10.1126/science.163.3863.150. PMID 5762760. 
  9. ^ a b Adl SM, Simpson AG, Farmer MA, et al. (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". J. Eukaryot. Microbiol. 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x. PMID 16248873. 
  10. ^ Cavalier-Smith T, Chao EE (October 2003). "Phylogeny and classification of phylum Cercozoa (Protozoa)". Protist 154 (3-4): 341–58. doi:10.1078/143446103322454112. PMID 14658494. 
  11. ^ Laura Wegener Parfrey, Erika Barbero, Elyse Lasser, Micah Dunthorn, Debashish Bhattacharya, David J Patterson, and Laura A Katz (2006 December). "Evaluating Support for the Current Classification of Eukaryotic Diversity". PLoS Genet. 2 (12): e220. doi:10.1371/journal.pgen.0020220. PMID 17194223. 
  12. ^ Talman AM, Domarle O, McKenzie FE, Ariey F, Robert V (July 2004). "Gametocytogenesis: the puberty of Plasmodium falciparum". Malar. J. 3: 24. doi:10.1186/1475-2875-3-24. PMID 15253774. 
  13. ^ Tibayrenc M, Kjellberg F, Arnaud J, et al. (June 1991). "Are eukaryotic microorganisms clonal or sexual? A population genetics vantage". Proc. Natl. Acad. Sci. U.S.A. 88 (12): 5129–33. doi:10.1073/pnas.88.12.5129. PMID 1675793. PMC 51825. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=1675793. 

External links


Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

See also protist

German

Noun

Protist m.
  1. protist (eukaryotic unicellular organisms of the kingdom Protoctista)
This German entry was created from the translations listed at protist. .It may be less reliable than other entries, and may be missing parts of speech or additional senses.^ The Archaezoa are primitive unicellular eukaryotes; primitive in the sense that they may better resemble the ancestral eukaryote than do less primitive eukaryotes .

^ Accordingly, preferred polypeptides or derivatives thereof may have less than 18 amino acids.
  • Treatment of Fungal and/or Protist Infections - Patent application 1 February 2010 3:45 UTC www.faqs.org [Source type: Reference]

Please also see
Protist in the German Wiktionary. This notice will be removed when the entry is checked. (more information) December 2008

Simple English

Protists are single-celled eukaryotes, which are a type of organism. Some autotrophic (which means they make their own food by photosynthesis), and others are heterotrophic (which means they eat organic material).

Most protists are very small. They are made up of one or a few cells at best – they are microscopic and therefore usually invisible to the naked eye. Some algae are protists, if they are single-celled. Many protists are part of the plankton and are very important for the ecosystem. The cells found in protists may be extremely complex, and are often little understood. It is now possible to do DNA sequencing, and a number of protists have been analysed. The results show that the Protista is not a monophyletic group. It is paraphyletic, and not a single clade. The taxonomy of the Protista is therefore rather confused.

Some protists cause diseases. Plasmodium falciparum causes malaria; sleeping sickness is also caused by a protist.

An example of a single celled organism in the protist kingdom is the Paramecium or "slipper animalcule." The Paramecium moves using its small, hair-like fibers called cilia, and eats using the cilia to sweep the food into its food vacuole. Other protists can be amoebas, which move by extending pseudopods and flowing into them, or flowing around food particles and engulfing them.

Nutrition in protists
Nutritional type Source of energy Source of carbon Examples
 Phototrophs   Sunlight   Organic compounds or carbon fixation  Algae, Dinoflagellates or Euglena 
 Organotrophs  Heterotrophs  Organic compounds   Organic compounds   Apicomplexa, Trypanosomes or Amoebae 

Origin and taxonomy

Protists are not a monophyletic clade. The term is a convenient holdall for about 20 different kinds of single-celle eukaryotes. They differ in their cell organelles, specialised units which carry out well-defined functions, like mitochondria and plastids. This proves they have made the transition from prokaryotes in different ways. It is fairly clear now that all or most of these organelles have their origin in once-independent prokaryotes (bacteria or archaea), and that the eukaryote cell is a 'community of micro-organisms' working together in 'a marriage of convenience'.[1][2][3][4] Admittedly, the Protista is a collection of disparate single-celled forms, but while a more sophisticated taxonomy is in flux (changing), Protista is still a useful term.

References

  1. Margulis L. and McMenamin 1990. Marriage of convenience. The Sciences 30, 31-36.
  2. Margulis L & Dolan M.F. 2002. Early life: evolution on the Precambrian Earth. 2nd ed, Jones & Bartlett, Boston. p89
  3. Margulis L. Schwartz K.V. & Dolan M. 1999. Diversity of life: the illustrated guide to the five kingdoms. Jones & Bartlett, Boston, p94. In this work the authors propose 19 phyla for the Protista, and call this 'Kingdom' the 'Protoctista', a term which is unfortunately almost unpronounceable.
  4. Dyer B.D. and Obar R.A. 1994. Tracing the history of eukaryotic cells. Columbia N.Y.
frr:Uurdiarten


Citable sentences

Up to date as of December 30, 2010

Here are sentences from other pages on Protist, which are similar to those in the above article.








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