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Trebouxiophyceae Genera
The Trebouxiophyceae, also known as trebouxiophytes, are a class of green algae, in the division Chlorophyta. Members of this class are single-celled, colonial, or multicellular and are found in freshwater, terrestrial or marine habitats worldwide. Many taxa in the Trebouxiophyceae form symbiotic relationships with other organisms; in particular, the majority of phycobionts within lichens are trebouxiophytes. A number of taxa have also lost the ability to photosynthesize, and have evolved to become parasitic; examples include '' Prototheca'' and '' Helicosporidium''. Trebouxiophyceae was originally defined by ultrastructural characteristics, but is now generally circumscribed based on phylogenetics, particularly based on the 18S rDNA locus. As of 2024, Trebouxiophyceae contains 211 genera and about 925 species. Morphology Members of the Trebouxiophyceae are microscopic or macroscopic organisms which exist in a variety of forms: non-flagellate coccoid or elliptical single cells, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorella Vulgaris
''Chlorella vulgaris'' is a species of green microalga in the division Chlorophyta. This unicellular alga was discovered in 1890 by Martinus Beijerinck, Martinus Willem Beijerinck as the first microalga with a well-defined nucleus. It is the type species of the genus ''Chlorella''. It is found in freshwater and terrestrial habitats, and has a cosmopolitan distribution. ''Chlorella vulgaris'' has a number of potential applications in science, such as biofuel, livestock feed, and wastewater treatment. Beginning in the 1990s, German scientists noticed the high protein content of ''C. vulgaris'' and began to consider it as a new food source. Japan is currently the largest consumer of ''Chlorella'', both for nutritional and therapeutic purposes, and it is used as a dietary supplement or protein-rich food additive in several countries worldwide. Description ''C. vulgaris'' is a green Eukaryote, eukaryotic microalga. The cells are 4–10 μm in diameter, and are spherical. The chloropl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrenoid
Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''Annu. Rev. Plant Biol.'', 56, 99-131. and in a single group of land plants, the hornworts.Villarreal, J. C., & Renner, S. S. (2012) Hornwort pyrenoids, carbon-concentrating structures, evolved and were lost at least five times during the last 100 million years. ''Proceedings of the National Academy of Sciences'',109(46), 1873-1887. Pyrenoids are associated with the operation of a carbon-concentrating mechanism (CCM). Their main function is to act as centres of carbon dioxide (CO2) fixation, by generating and maintaining a CO2-rich environment around the photosynthesis, photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Pyrenoids therefore seem to have a role analogous to that of carboxysomes in cyanobacteria. ... [...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] |
Phycoplast
image:Phycoplast.png, Schematic representation of types of cytokinesis in the green algae: 1) Phycoplast formation with cleavage furrow (e.g. ''Chlamydomonas''); 2) Cleavage furrow and persistent telophase spindle (e.g. ''Klebsormidium''); 3) Phycoplast and cell plate formation (e.g. ''Fritschiella''); 4) Persistent telophase spindle/phragmoplast with cell plate formation (e.g. ''Coleochaete'') The phycoplast is a microtubule structure observed during cytokinesis in members of the '' Chlorophytina'', the largest and most well known subphylum of chlorophyte green algae. Cytokinesis in green algae occurs via a diverse range of mechanisms, including cleavage furrows in some algae and cell plates in others. Plants (= Chloroplastida) of the clade '' Phragmoplastophyta'' (a subgroup of charophytes which includes the land plants, desmids, water silk, stoneworts etc.) use structures called phragmoplasts to organize and guide the growing cell plate. In these plants, the microtubules of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telophase
Telophase () is the final stage in both meiosis and mitosis in a eukaryotic cell. During telophase, the effects of prophase and prometaphase (the nucleolus and nuclear membrane disintegrating) are reversed. As chromosomes reach the cell poles, a nuclear envelope is re-assembled around each set of chromatids, the nucleoli reappear, and chromosomes begin to decondense back into the expanded chromatin that is present during interphase. The mitotic spindle is disassembled and remaining spindle microtubules are depolymerized. Telophase accounts for approximately 2% of the cell cycle's duration. Cytokinesis typically begins before late telophase and, when complete, segregates the two daughter nuclei between a pair of separate daughter cells. Telophase is primarily driven by the dephosphorylation of mitotic cyclin-dependent kinase (Cdk) substrates. Dephosphorylation of Cdk substrates The phosphorylation of the protein targets of M-Cdks (Mitotic Cyclin-dependent Kinases) drives sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spindle Apparatus
In cell biology, the spindle apparatus is the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter Cell (biology), cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell. Besides chromosomes, the spindle apparatus is composed of hundreds of proteins. Microtubules comprise the most abundant components of the machinery. Spindle structure Attachment of microtubules to chromosomes is mediated by kinetochores, which actively monitor spindle assembly checkpoint, spindle formation and prevent premature anaphase onset. Microtubule polymerization and depolymerization dynamic drive chromosome congression. Depolymerization of microtubules generates tension at kinetochores; bipolar attachment of sister kinetochores to microtubu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagella
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many protists with flagella are known as flagellates. A microorganism may have from one to many flagella. A gram-negative bacterium '' Helicobacter pylori'', for example, uses its flagella to propel itself through the stomach to reach the mucous lining where it may colonise the epithelium and potentially cause gastritis, and ulcers – a risk factor for stomach cancer. In some swarming bacteria, the flagellum can also function as a sensory organelle, being sensitive to wetness outside the cell. Across the three domains of Bacteria, Archaea, and Eukaryota, the flagellum has a different structure, protein composition, and mechanism of propulsion but shares the same function of providing motility. The Latin word means " whip" to describe its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basal Bodies
A basal body (synonymous with basal granule, kinetosome, and in older cytological literature with blepharoplast) is a protein structure found at the base of a eukaryotic undulipodium (cilium or flagellum). The basal body was named by Theodor Wilhelm Engelmann in 1880. It is formed from a centriole and several additional protein structures, and is, essentially, a modified centriole. The basal body serves as a nucleation site for the growth of the axoneme microtubules. Centrioles, from which basal bodies are derived, act as anchoring sites for proteins that in turn anchor microtubules, and are known as the microtubule organizing center (MTOC). These microtubules provide structure and facilitate movement of vesicles and organelles within many eukaryotic cells. Assembly, structure Cilia and basal bodies form during quiescence or the G1 phase of the cell cycle. Before the cell enters G1 phase, i.e. before the formation of the cilium, the mother centriole serves as a componen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiomorphic
In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and synapomorphy all mean a trait shared between species because they share an ancestral species. Apomorphic and synapomorphic characteristics convey much information about evolutionary clades and can be used to define taxa. However, plesiomorphic and symplesiomorphic characteristics cannot. The term ''symplesiomorphy'' was introduced in 1950 by German entomologist Willi Hennig. Examples A backbone is a plesiomorphic trait shared by birds and mammals, and does not help in placing an animal in one or the other of these two clades. Birds and mammals share this trait because both clades are descended from the same far distant ancestor. Other clades, e.g. snakes, lizards, turtles, fish, frogs, all have backbones and none are either birds n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oogamy
Oogamy is a form of anisogamy where the gametes differ in both size and form. In oogamy the large female gamete (also known as ovum) is immotile, while the small male gamete (also known as spermatozoon) is mobile. Oogamy is a common form of anisogamy, with almost all animals and land plants being oogamous. Oogamy is found in most sexually reproducing species, including all vertebrates, land plants, and some algae. The ancestral state of sexual reproduction is believed to be isogamy, with oogamy evolving through anisogamy. Once oogamy evolves, males and females typically differ in various aspects. Internal fertilization may have originated from oogamy, although some studies suggest that oogamy in certain species may have evolved before the transition from external to internal fertilization. In streptophytes, oogamy occurred before the split from green algae. Occurrence Oogamy is found in almost all animal species that reproduce sexually. There are exceptions, such as the op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anisogamy
Different forms of anisogamy: A) anisogamy of motile cells, B) 283x283px Anisogamy is a form of sexual reproduction">egg cell">oogamy (egg cell and sperm cell), C) anisogamy of non-motile cells (egg cell and spermatia).">283x283px Anisogamy is a form of sexual reproduction that involves the union or fusion of two gametes that differ in size and/or form. The smaller gamete is male, a ''microgamete'' or sperm cell, whereas the larger gamete is female, a larger ''macrogamete'' or typically an egg cell. Anisogamy is predominant among multicellular organisms. In both plants and animals, gamete size difference is the fundamental difference between females and males. Anisogamy most likely evolved from isogamy. Since the biological definition of male and female is based on gamete size, the evolution of anisogamy is viewed as the evolutionary origin of male and female sexes. Anisogamy is an outcome of both natural selection and sexual selection, and led the sexes to different prima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isogamy
Isogamy is a form of sexual reproduction that involves Gamete, gametes of the same Morphology (biology), morphology (indistinguishable in shape and size), and is found in most Unicellular organism, unicellular eukaryotes. Because both gametes look alike, they generally cannot be classified as male or female. Instead, organisms that reproduce through isogamy are said to have different Mating type, mating types, most commonly noted as "+" and "−" strains. Etymology The etymology of isogamy derives from the Greek adjective ''isos'' (meaning equal) and the Greek verb ''gameo'' (meaning to have sex/to reproduce), eventually meaning "equal reproduction" which refers to a hypothetical initial model of equal contribution of resources by both gametes to a zygote in contrast to a later evolutional stage of anisogamy. The term isogamy was first used in the year 1891. Characteristics of isogamous species Isogamous species often have two Mating type, mating types (heterothallism), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
