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Dasycladales
Dasycladales is an Order (biology), order of large unicellular green algae in the class Ulvophyceae. It contains two families, the Dasycladaceae and the Polyphysaceae. These single celled algae are from 2 mm to 200 mm long. They live on substrates in shallow warm (>20 °C) euhaline tropical marine waters, usually less than 20 meters deep, and protected from waves. They are very large cells. They are able to attain these sizes without numerous internal cell wells because they build calcium carbonate shells around themselves. They contain only one Cell nucleus, nucleus in their vegetative stage, which remains in the bottom of the cell in the holdfast (biology), holdfast at the substrate. Only when they are ready to produce gametes does the nucleus undergo meiosis and then numerous mitosis, mitoses into many nuclei which then migrate into the gametangia at the top of the alga. Because the nucleus is safely hidden in the holdfast, the cells easily regenerate if t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ulvophyceae
The Ulvophyceae or ulvophytes are a class of green algae, distinguished mainly on the basis of Ultrastructure, ultrastructural morphology, Biological life cycle, life cycle and molecular phylogenetics, molecular phylogenetic data. The sea lettuce, sea lettuce, ''Ulva'', belongs here. Other well-known members include ''Caulerpa'', ''Codium'', ''Acetabularia'', ''Cladophora'', ''Trentepohlia (alga), Trentepohlia'' and ''Monostroma''. The Ulvophytes are diverse in their Morphology (biology), morphology and their habitat (ecology), habitat. Most are seaweeds such as those listed above. Others, such as ''Rhizoclonium'', ''Pithophora'' and some species of ''Cladophora'' live in fresh water and in some areas are considered weeds. Morphology Ulvophycean algae are diverse in morphology. The thalli are typically colonial (some are unicellular). A few taxa have flagella in their vegetative stage, such as ''Oltmannsiellopsis''. Common forms include filaments (both unbranched and branched) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphysaceae
The Polyphysaceae is a taxonomic family (biology), family of green algae, one of three families in the order Dasycladales. For single-celled organisms, they are huge, growing to nearly a foot long in some cases. References Dasycladales Ulvophyceae families {{Ulvophyceae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclocrinitids
Cyclocrinitids are an early (mid-Ordovician–early-Silurian) Dasycladalean algae, resembling but probably not closely related to the Receptaculitid ''Receptaculites'' is the name-bearing genus for an extinct group of conspicuous benthic marine genera, the receptaculitids (formally Receptaculitaceae or Receptaculitidae), that lived from the Early Ordovician through the Permian The Permian ...s. References Dasycladales {{silurian-plant-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Receptaculitaceae
''Receptaculites'' is the name-bearing genus for an extinct group of conspicuous benthic marine genera, the receptaculitids (formally Receptaculitaceae or Receptaculitidae), that lived from the Early Ordovician through the Permian period, peaking in the Middle Ordovician. The group's phylogenetic origin has long been obscure, with some arguing that they were calcareous algae, probably of the order Dasycladales.Byrnes, J.G. 1968. Notes on the nature and environmental significance of the Receptaculitaceae. Lethaia, vol. 1, p. 368-381. Receptaculitids lived in warm, shallow seas, but consensus disagreeing. They have been described from all continents except Antarctica. In some areas they were important reef-formers, and they also occur as isolated specimens. ''Receptaculites'' and its relatives have a double-spiral, radiating pattern of rhombus-shaped plates supported by spindle-like objects called meroms. Fossils can usually be identified by the intersecting patterns of clockwise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dasycladaceae
The Dasycladaceae is one of the two extant family (biology), families of green algae of the order Dasycladales. When found in Palaeozoic limestones, they typically indicate depositional depth of less than 5m.See the National Center for Biotechnology Information, NCBI]webpage on Dasycladaceae Data extracted from the Genera * †''Acicularia'' * †''Acroporella'' * ''Amicus (alga), Amicus'' * ''Anatolipora'' * ''Andrusoporella'' * ''Anfractuosoporella'' * †''Anisoporella'' * †''Anthracoporella'' * †''Archaeocladus'' * †''Atractyliopsis'' * ''Batophora'' * †''Beresella'' * ''Bornetella'' * †''Chinianella'' * ''Chloroclados'' * †''Clavapora'' * †''Clavaporella'' * ''Connexia'' * ''Cylindroporella'' * ''Cymopolia'' * ''Dasycladus'' * ''Dissocladella'' * †''Dvinella'' * †''Endoina'' * †''Eoclypeina'' * ''Eogoniolina'' * †''Eovelebitella'' * †''Epimastopora'' * †''Euteutloporella'' * †''Favoporella'' * †''Fourcadella'' * †''Genotella'' * †''Gonioli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitosis
Mitosis () is a part of the cell cycle in eukaryote, eukaryotic cells in which replicated chromosomes are separated into two new Cell nucleus, nuclei. Cell division by mitosis is an equational division which gives rise to genetically identical cells in which the total number of chromosomes is maintained. Mitosis is preceded by the S phase of interphase (during which DNA replication occurs) and is followed by telophase and cytokinesis, which divide the cytoplasm, organelles, and cell membrane of one cell into two new cell (biology), cells containing roughly equal shares of these cellular components. The different stages of mitosis altogether define the mitotic phase (M phase) of a cell cycle—the cell division, division of the mother cell into two daughter cells genetically identical to each other. The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are preprophase (specific to plant ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoplasm
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are the cytosol (a gel-like substance), the cell's internal sub-structures, and various cytoplasmic inclusions. In eukaryotes the cytoplasm also includes the nucleus, and other membrane-bound organelles.The cytoplasm is about 80% water and is usually colorless. The submicroscopic ground cell substance, or cytoplasmic matrix, that remains after the exclusion of the cell organelles and particles is groundplasm. It is the hyaloplasm of light microscopy, a highly complex, polyphasic system in which all resolvable cytoplasmic elements are suspended, including the larger organelles such as the ribosomes, mitochondria, plant plasti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanometer
330px, Different lengths as in respect to the Molecule">molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm), or nanometer (American spelling Despite the various list of dialects of English, English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography, the two most notable variati ...), is a units of measurement, unit of length in the International System of Units (SI), equal to one billionth (short scale) or one thousand million (long scale) of a metre, meter (0.000000001 m) and to 1000 picometres. One nanometre can be expressed in scientific notation as 1 × 10−9 m and as m. History The nanometre was formerly known as the "''millimicrometre''" – or, more commonly, the "''millimicron''" for short – since it is of a micrometre, micrometer. It was often de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gametangia
A gametangium (: gametangia) is a sex organ or cell in which gametes are produced that is found in many multicellular protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...s, algae, Fungus, fungi, and the gametophytes of plants. In contrast to gametogenesis in animals, a gametangium is a haploid structure and formation of gametes does not involve meiosis. Types of gametangia Depending on the type of gamete produced in a gametangium, several types can be distinguished. Female Female gametangia are most commonly called Archegonium, archegonia. They produce egg cells and are the sites for fertilization. Archegonia are common in algae and primitive plants as well as gymnosperms. In flowering plants, they are replaced by the embryo sac inside the ovule. Male The male gametangia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
