| Euglenozoa | ||||||
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Euglenoidea |
The Euglenozoa are a large group of flagellate protozoa. Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex The excavates are a major assemblage of Protists often known as Excavata. Professor Thomas (Tom Cavalier-Smith (born October 21 1942) FRS, FRSC, NERC Professorial Fellow is a Professor of The euglenids (or euglenoids) are one of the best-known groups of Flagellates commonly found in freshwater especially when it is rich in organic materials with a The kinetoplastids are a group of Flagellate Protozoa, including a number of Parasites responsible for serious diseases in humans and other animals as well Flagellates are cells with one or more whip-like organelles called flagella. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. There are two main subgroups, the euglenids and kinetoplastids. The euglenids (or euglenoids) are one of the best-known groups of Flagellates commonly found in freshwater especially when it is rich in organic materials with a The kinetoplastids are a group of Flagellate Protozoa, including a number of Parasites responsible for serious diseases in humans and other animals as well Euglenozoa are unicellular, mostly around 15-40 µm in size, although some euglenids get up to 500 µm long.
Most euglenozoa have two flagella, which are inserted parallel to one another in an apical or subapical pocket. In some these are associated with a cytostome or mouth, used to ingest bacteria or other small organisms. A cytostome or cell mouth is a part of a cell specialized for Phagocytosis, usually in the form of a Microtubule -supported funnel or groove The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have This is supported by one of three sets of microtubules that arise from the flagellar bases; the other two support the dorsal and ventral surfaces of the cell. Microtubules are one of the components of the Cytoskeleton. They have a diameter of 25 nm and length varying from 200 nanometers to 25 micrometers [2]
Some other euglenozoa feed through the absorption, and many euglenids possess chloroplasts and so obtain energy through photosynthesis. Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. These chloroplasts are surrounded by three membranes and contain chlorophylls a and b, along with other pigments[1], so are probably derived from a captured green alga. Chlorophyll is a green Pigment found in most Plants Algae and Cyanobacteria. The green algae (singular green alga) are the large group of Algae from which the Embryophytes (higher plants emerged Reproduction occurs exclusively through cell division. During mitosis, the nuclear membrane remains intact, and the spindle microtubules form inside of it. Mitosis is the process in which a Eukaryotic cell separates the Chromosomes in its Cell nucleus, into two identical sets in two daughter nuclei [2]
The group is characterized by the ultrastructure of the flagella. In addition to the normal supporting microtubules or axoneme, each contains a rod (called paraxonemal), which has a tubular structure in one flagellum and a latticed structure in the other. Chlamydomonas TEM 17jpg|thumb|Micrograph of thin x-section cut through Chlamydomonas axoneme]]Numerous Eukaryotic cells carry whip-like appendages ( Cilia Based on this, two smaller groups have been included here: the diplonemids and Postgaardi. [3]
The euglenozoa are generally accepted as monophyletic. They are related to Percolozoa; the two share mitochondria with disc-shaped cristae, which only occurs in a few other groups. The Percolozoa are a group of colourless Protozoa, including many that can transform between Amoeboid, Flagellate, and encysted stages [4] Both probably belong to a larger group of eukaryotes called the excavates. The excavates are a major assemblage of Protists often known as Excavata. [5]
References
- ^ a b T. Cavalier-Smith (1981). "Eukaryote Kingdoms: Seven or Nine?". BioSystems 14: 461–481. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ a b David J. Patterson (1999). "The Diversity of Eukaryotes". American Naturalist 145: S96–S124.
- ^ Alastair G. B. Simpson (1997). "The Identity and Composition of Euglenozoa". Archiv für Protistenkunde 148: 318–328.
- ^ Baldauf et al. (2000). "A Kingdom-Level Phylogeny of Eukaryotes Based On Combined Protein Data". Science 290: 972–977. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 11062127.
- ^ Alastair G. Simpson (2003). "Cytoskeletal organization, phylogenetic affinities and systematics in the contentious taxon Excavata (Eukaryota)". International Journal of Systematic and Evolutionary Microbiology 53: 1759–1777. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 14657103.
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