protoctist


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Related to protoctist: Protoctista, fungi

pro·toc·tist

 (prə-tōk′tĭst)
n.
Any of various eukaryotic organisms belonging to the kingdom Protoctista in some classification systems. Protoctists include unicellular and multicellular organisms that are not fungi, plants, or animals. They are usually now referred to as protists.

[From New Latin Prōtoctista, kingdom name : Greek prōto-, proto- + Greek ktistos, produced, created (from ktizein, to create, establish; see tkei- in Indo-European roots).]

protoctist

(prəʊˈtɒktɪst)
n
(Biology) (in modern biological classifications) any unicellular or simple multicellular organism belonging to the kingdom Protoctista, which includes protozoans, algae, and slime moulds
[C19: from New Latin protoctista, perhaps from Greek prōtotokos first born]

pro·toc·tist

(prə-tŏk′tĭst)
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.protoctist - any of the unicellular protistsprotoctist - any of the unicellular protists  
microorganism, micro-organism - any organism of microscopic size
kingdom Protoctista, Protoctista - in most modern classifications, replacement for the Protista; includes: Protozoa; Euglenophyta; Chlorophyta; Cryptophyta; Heterokontophyta; Rhodophyta; unicellular protists and their descendant multicellular organisms: regarded as distinct from plants and animals
protozoan, protozoon - any of diverse minute acellular or unicellular organisms usually nonphotosynthetic
alga, algae - primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves
References in periodicals archive ?
The karyomastigont, an organellar system that includes the nucleus, the nuclear connector, and kinetosome-centrioles in many protoctist and animal cells, is a conspicuous component of the cytoskeleton.
The Protoctist Kingdom (0761418180), Reptile Class (0761418202), Insect Class (0761418199), Flowering Plant Kingdom (0761418172) and Primate Order (0761-418164) by Stefoff each survey kingdoms and species, classification methods, physical traits, adaptations, and life cycles.
Nearly one in five species in the fungal kingdom forms a composite with an alga, which is from the protist, or protoctist, kingdom.
Kala-azar, or visceral leishmaniasis, is caused by the presence in the blood and some organs, such as liver, spleen, and bone marrow, of the parasitic kinetoplastid protoctist Leishmania donovani, which is transmitted by the bite of a sandfly Phlebotomus.
In particular, the role of the microheterotrophs, protoctist microorganisms that feed on microalgae and bacteria, may be of great importance in the food webs of the Antarctic Ocean.
The second type of sex is hypersex, characteristic of the protoctists; microorganisms that comprise one of the five kingdoms of living organisms (i.e., protoctista; plantae, animalia, fungi, and bacteria).
As Case noted, attempted reconciliation of five Kingdoms (Bacteria, Protoctists, Animals, Plants, Fungi) with three Domains (Bacteria, Archaea, Eucarya) resulted in a "compromise" of six kingdoms (Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia)--an outcome that does not fully represent the intent of either the five-kingdom or three-domain system.
The five kingdoms system identifies five categories of organisms as rational kingdom divisions: bacteria (the prokaryotic or nucleus-lacking microbes), protoctists (algae, slime molds, and other nucleated eukaryotic organisms formed by symbiosis from bacteria), fungi (mushrooms, molds, and yeasts, all of which reproduce by spores), plants (organisms that develop from spores and embryos retained by the mother's tissue), and animals (organisms that develop from eggs fertilized by sperm).
Class 2 Foraminifera (Reticulopodate with Shell, Foraminiferans, Forams) Phylum 4 Xenophyophora (Large Deep-Sea Benthic Protoctists)
He rejoices in turns of phrase like "protoctists pop out of their protective cysts" and "the great mycelial clot beneath a toadstool"; of the burning of fossil fuels he remarks that the carbon released in the process "floods the carbon cycle, as if the dead should arise from their graves and flood the job market." His assessment of current agricultural practices is as memorable as it is severe:
protoctists, and bacteria], animals may be defined as multicellular,
For decades, most biologists accepted the classification of all life into five kingdoms: Bacteria (or Monera), Protoctists (protists and their macroscopic relatives), Animals, Plants, and Fungi (Figure 1).