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Euglena
''Euglena'' is a genus of Unicellular organism, single-celled, flagellate eukaryotes. It is the best-known and most widely studied member of the class Euglenoidea, a diverse group containing some 54 genera and at least 200 species. Species of ''Euglena'' are found in fresh water and salt water. They are often abundant in quiet inland waters where they may bloom in numbers sufficient to color the surface of ponds and ditches green (''Euglena viridis, E. viridis'') or red (''Euglena sanguinea, E. sanguinea''). The species ''Euglena gracilis'' has been used extensively in the laboratory as a model organism. Most species of ''Euglena'' have photosynthesizing chloroplasts within the body of the cell, which enable them to feed by autotrophy, like plants. However, they can also take nourishment heterotrophically, like animals. Since ''Euglena'' have features of both animals and plants, early taxonomists, working within the Linnaean taxonomy, Linnaean two-kingdom system of bio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euglena Viridis
''Euglena viridis'' is a single-celled species of euglenoid, a type of microalgae. It is one of the oldest-known species of ''Euglena'', and was first seen by Antonie van Leeuwenhoek in 1764. It is found in freshwater habitats worldwide. ''Euglena viridis'', along with other ''Euglena'' species, are well-studied. Cells of ''E. viridis'' have a secondary chloroplast. The chloroplast is bounded by three layers of membrane without a nucleomorph. Taxonomy ''Euglena viridis'' is one of the first ''Euglena'' species named when Ehrenberg established the genus ''Euglena''. ''Euglena viridis'' is also the type species of this genus. The whole group of Euglenozoa was originally placed in a group called Excavata. However, Excavata has been thought not monophyletic and is divided into several groups. Now, Euglenozoa is placed below a group in Discoba. Phylogeny According to molecular evidence, phylogenetic relationships between ''Euglena viridis'' and its close relatives are as follo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euglenoid Movement
Euglenids or euglenoids are one of the best-known groups of eukaryotic flagellates: single-celled organisms with flagella, or whip-like tails. They are classified in the phylum Euglenophyta, class Euglenida or Euglenoidea. Euglenids are commonly found in fresh water, especially when it is rich in organic materials, but they have a few marine and endosymbiotic members. Many euglenids feed by phagocytosis, or strictly by diffusion. A monophyletic subgroup known as Euglenophyceae have chloroplasts and produce their own food through photosynthesis. This group contains the carbohydrate paramylon. Euglenids split from other Euglenozoa (a larger group of flagellates) more than a billion years ago. The plastids (membranous organelles) in all extant photosynthetic species result from secondary endosymbiosis between a euglenid and a green alga. Structure Euglenoids are distinguished mainly by the presence of a type of cell covering called a pellicle. Within its taxon, the pellicle is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euglena Gracilis
''Euglena gracilis'' is a freshwater species of euglenid, a microscopic type of algae, in the genus ''Euglena''. It has secondary chloroplasts, and is a mixotroph able to feed by photosynthesis or phagocytosis. It has a highly flexible cell surface, allowing it to change shape from a thin cell up to 100 μm long to a sphere of approximately 20 μm. Each cell has two flagella, only one of which emerges from the flagellar pocket (reservoir) in the anterior of the cell, and can move by swimming, or by so-called "euglenoid" movement across surfaces. ''E. gracilis'' has been used extensively in the laboratory as a model organism, particularly for studying cell biology and biochemistry. Other areas of their use include studies of photosynthesis, photoreception, and the relationship of molecular structure to the biological function of subcellular particles, among others. ''Euglena gracilis'' is the most studied member of the Euglenaceae. ''E. gracilis'' was discovered as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euglena Sanguinea
''Euglena sanguinea'' is a species of euglenid of the genus ''Euglena''. It is a single-celled alga that is found in freshwater habitats, and has a cosmopolitan distribution. As the specific epithet ''sanguinea'' suggests, it is often coloured red due to the presence of astaxanthin, and the cells can be populous enough to form blooms that colour the water red. Description ''Euglena sanguinea'' is a single-celled organism, with cells 61–150 μm long and 17–35 μm wide. The cells are spindle-shaped with a rounded anterior and a pointed posterior; the cell is surrounded by a pellicle which is spirally striated. Each cell has numerous (>15) chloroplasts in the shape of highly concave plates. Chloroplasts are in the shape of highly concave plates and are deeply dissected into long, ribbon-like bands which follow the contour of the cell and form spiral rows. The center of each chloroplast is embedded deeper inside the cell, and contains a single double-sheathed pyrenoid. Spindle- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peranema
''Peranema'' is a genus of free-living phagotrophic euglenids (Euglenida; Euglenozoa; Excavata). There are more than 20 nominal species, varying in size between 8 and 200 micrometers. ''Peranema'' cells are gliding flagellates found in freshwater lakes, ponds and ditches, and are often abundant at the bottom of stagnant pools rich in decaying organic material. Although they belong to the class Euglenoidea, and are morphologically similar to the green ''Euglena'', ''Peranema'' have no chloroplasts, and do not conduct autotrophy. Instead, they capture live prey, such as yeast, bacteria and other flagellates, consuming them with the help of a rigid feeding apparatus called a "rod-organ." Unlike the green euglenids, they lack both an Eyespot apparatus, eyespot (stigma), and the Eyespot apparatus, paraflagellar body (photoreceptor) that is normally coupled with that organelle. However, while ''Peranema'' lack a localized photoreceptor, they do possess the light-sensitive protei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metaboly
Spirocuta () is a clade of euglenids, single-celled eukaryotes or protists belonging to the phylum Euglenozoa. They are distinguished from other euglenids by active deformation of their cell shape, a process called euglenid motion or metaboly. This is made possible by a high number of spirally arranged protein strips that run below their cell membrane and confer the cell with flexibility. These strips compose the helicoidal pellicle (biology), pellicle, a trait referenced by the alternative name Helicales. Description Spirocuta is a group of flagellates, unicellular eukaryotes or protists with one or two flagella for locomotion in the anterior region of the cell. The move through a gliding motility, gliding motion in contact with the substrate to propel the cell forward. Like other members of the Euglenida, their cells are lined by a pellicle (biology), pellicle composed of proteinaceous strips that interlock with each other, and are spirally arranged underneath the cell membran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discoplastis
''Discoplastis'' is a genus of euglenoid algae belonging to the family Phacaceae. The species of this genus are found in Europe, Northern America, Southeastern Asia and Australia. ''Discoplastis'' consists of solitary, free-living cells with one emergent flagellum. The cells have a flexible, spirally striated pellicle and are therefore capable of metaboly. When swimming, the cells are a variety of different but characteristic shapes (cylindrical, fusiform, hourglass-shaped, etc.). The posterior of the cell ends in a pointed, colorless cell. Within each cell there are numerous small, discoid chloroplast lacking pyrenoids. Cells have paramylon grains; the paramylon grains may be monomorphic (all small) or dimorphic (some large, some small). As with other euglenoids, the cell has a reddish eyespot (stigma). ''Discoplastis'' can be distinguished by to the combination of small, discoid parietal chloroplasts without pyrenoids (a synapomorphy for the family Phacaceae), and its fle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Endosymbiosis
Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes (more closely related to the Bacteria than to the Archaea) taken one inside the other in endosymbiosis. Mitochondria appear to be phylogenetically related to Rickettsiales bacteria, while chloroplasts are thought to be related to cyanobacteria. The idea that chloroplasts were originally independent organisms that merged into a symbiotic relationship with other one-celled organisms dates back to the 19th century, when it was espoused by researchers such as Andreas Schimper. The endosymbiotic theory was articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by Lynn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protista
A protist ( ) or protoctist is any Eukaryote, eukaryotic organism that is not an animal, Embryophyte, land plant, or fungus. Protists do not form a Clade, natural group, or clade, but are a Paraphyly, paraphyletic grouping of all descendants of the last eukaryotic common ancestor excluding land plants, animals, and fungi. Protists were historically regarded as a separate taxonomic rank, taxonomic kingdom (biology), kingdom known as Protista or Protoctista. With the advent of phylogenetic analysis and electron microscopy studies, the use of Protista as a formal taxon was gradually abandoned. In modern classifications, protists are spread across several eukaryotic clades called supergroup (biology), supergroups, such as Archaeplastida (photoautotrophs that includes land plants), SAR supergroup, SAR, Obazoa (which includes fungi and animals), Amoebozoa and "Excavata". Protists represent an extremely large genetic diversity, genetic and ecological diversity in all environments, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroplast
A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which capture the Radiant energy, energy from sunlight and convert it to chemical energy and release oxygen. The chemical energy created is then used to make sugar and other organic molecules from carbon dioxide in a process called the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in some unicellular algae, up to 100 in plants like ''Arabidopsis'' and wheat. Chloroplasts are highly dynamic—they circulate and are moved around within cells. Their behavior is strongly influenced by environmental factors like light color and intensity. Chloroplasts cannot be made anew by the plant cell and must ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unicellular Organism
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms. Most prokaryotes are unicellular and are classified into bacteria and archaea. Many eukaryotes are multicellular, but some are unicellular such as protozoa, unicellular algae, and unicellular fungi. Unicellular organisms are thought to be the oldest form of life, with early organisms emerging 3.5–3.8 billion years ago. Although some prokaryotes live in colonies, they are not specialised cells with differing functions. These organisms live together, and each cell must carry out all life processes to survive. In contrast, even the simplest multicellular organisms have cells that depend on each other to survive. Most multicellular organisms have a unicellular life-cycle stage. Gametes, for example, are reprodu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
