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Kinetin
Kinetin (/'kaɪnɪtɪn/) is a type of cytokinin, a class of plant hormone that promotes cell division. Kinetin was originally isolated by Carlos Miller and Skoog ''et al.'' as a compound from autoclaved herring sperm DNA that had cell division-promoting activity. It was given the name kinetin because of its ability to induce cell division, provided that auxin was present in the medium. Kinetin is often used in plant tissue culture for inducing formation of callus (in conjunction with auxin) and to regenerate shoot tissues from callus (with lower auxin concentration). For a long time, it was believed that kinetin was an artifact produced from the deoxyadenosine residues in DNA, which degrade on standing for long periods or when heated during the isolation procedure. Therefore, it was thought that kinetin does not occur naturally, but, since 1996, it has been shown by several researchers that kinetin exists naturally in the DNA of cells of almost all organisms tested so far, incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokinins
Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence. There are two types of cytokinins: adenine-type cytokinins represented by kinetin, zeatin, and 6-benzylaminopurine, and phenylurea-type cytokinins like diphenylurea and thidiazuron (TDZ). Most adenine-type cytokinins are synthesized in roots. Cambium and other actively dividing tissues also synthesize cytokinins. No phenylurea cytokinins have been found in plants. Cytokinins participate in local and long-distance signalling, with the same transport mechanism as purines and nucleosides. Typically, cytokinins are transported in the xylem. Cytokinins act in concert with auxin, another plant growth hormone. The two are complementary, having generally opposite effects. History The idea of specific substances required for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokinin
Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence. There are two types of cytokinins: adenine-type cytokinins represented by kinetin, zeatin, and 6-benzylaminopurine, and phenylurea-type cytokinins like diphenylurea and thidiazuron (TDZ). Most adenine-type cytokinins are synthesized in roots. Cambium and other actively dividing tissues also synthesize cytokinins. No phenylurea cytokinins have been found in plants. Cytokinins participate in local and long-distance signalling, with the same transport mechanism as purines and nucleosides. Typically, cytokinins are transported in the xylem. Cytokinins act in concert with auxin, another plant growth hormone. The two are complementary, having generally opposite effects. History The idea of specific substances required for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Folke K Skoog
Folke Karl Skoog (July 15, 1908 – February 15, 2001) was a Swedish-born American plant physiologist who was a pioneer in the field of plant growth regulators, particularly cytokinins. Skoog was a recipient of the National Medal of Science 1991. Born in Halland, Sweden, Skoog emigrated to the United States during a trip to California in 1925, and was naturalized as a citizen almost a decade later. He competed, and finished sixth in heat 2, in the 1500 meter race during the 1932 Summer Olympics. In 1936, he received his PhD in biology from Caltech for his work done with auxin, a plant hormone. In 1937, Skoog was a postdoctoral researcher with Dennis Robert Hoagland, and his professional career advanced significantly with his arrival at the University of Wisconsin–Madison in 1947. Carlos O. Miller discovered kinetin in 1954, and benzyladenine and related compounds were later synthesized in Skoog's lab. In 1962, Skoog and Toshio Murashige published what is probably the best ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytohormone
Plant hormone (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pathogen defense, stress tolerance and through to reproductive development. Unlike in animals (in which hormone production is restricted to specialized glands) each plant cell is capable of producing hormones. Went and Thimann coined the term "phytohormone" and used it in the title of their 1937 book. Phytohormones occur across the plant kingdom, and even in algae, where they have similar functions to those seen in higher plants. Some phytohormones also occur in microorganisms, such as unicellular fungi and bacteria, however in these cases they do not play a hormonal role and can better be regarded as secondary metabolites. Characteristics The word hormone is derived from Greek, meaning ''set in motion''. Plant hormones affect gene expres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute 1% of all described fungal species. Yeasts are unicellular organisms that evolved from multicellular ancestors, with some species having the ability to develop multicellular characteristics by forming strings of connected budding cells known as pseudohyphae or false hyphae. Yeast sizes vary greatly, depending on species and environment, typically measuring 3–4 µm in diameter, although some yeasts can grow to 40 µm in size. Most yeasts reproduce asexually by mitosis, and many do so by the asymmetric division process known as budding. With their single-celled growth habit, yeasts can be contrasted with molds, which grow hyphae. Fungal species that can take both forms (depending on temperature or other conditions) are ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicotiana Tabacum
''Nicotiana tabacum'', or cultivated tobacco, is an annually grown herbaceous plant of the ''Nicotiana'' genus. The plant is tropical in origin, is commonly grown throughout the world, and is often found in cultivation. It grows to heights between 1 and 2 meters (3' to 6'). Research is ongoing into its ancestry among wild ''Nicotiana'' species, but it is believed to be a hybrid of ''Nicotiana sylvestris'', '' Nicotiana tomentosiformis'', and possibly '' Nicotiana otophora''. It is the most commonly grown of all plants in the genus ''Nicotiana,'' the plants' leaves commercially grown to be processed into tobacco. Description It is an annual plant that grows high and is sticky hairy on all parts. The stems are thick and not very branched. The leaves can be over long with the blades ovate to elliptical, or obovate, pointed towards the front and, at the base, run down the stem or are sessile, encompassing the stem. The scented inflorescences are multi-branched panicles. The flow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists in growing abnormally, even if the original trigger is removed. This abnormal growth usually forms a mass, when it may be called a tumor. ICD-10 classifies neoplasms into four main groups: benign neoplasms, in situ neoplasms, malignant neoplasms, and neoplasms of uncertain or unknown behavior. Malignant neoplasms are also simply known as cancers and are the focus of oncology. Prior to the abnormal growth of tissue, as neoplasia, cells often undergo an abnormal pattern of growth, such as metaplasia or dysplasia. However, metaplasia or dysplasia does not always progress to neoplasia and can occur in other conditions as well. The word is from Ancient Greek 'new' and 'formation, creation'. Types A neoplasm can be benign, potentially m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coconut Milk
Coconut milk is an opaque, milky-white liquid extracted from the grated pulp of mature coconuts. The opacity and rich taste of coconut milk are due to its high oil content, most of which is saturated fat. Coconut milk is a traditional food ingredient used in Southeast Asia, Oceania, South Asia, and East Africa. It is also used for cooking in the Caribbean, tropical Latin America, and West Africa, where coconuts were introduced during the colonial era. Coconut milk is differentiated into subtypes based on fat content. They can be generalized into coconut cream (or thick coconut milk) with the highest amount of fat; coconut milk (or thin coconut milk) with a maximum of around 20% fat; and coconut skim milk with negligible amounts of fat. This terminology is not always followed in commercial coconut milk sold in western countries. Coconut milk can also be used to produce milk substitutes (differentiated as "coconut milk beverages"). These products are not the same as regular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aneuploidy
Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a ''euploid'' cell. An extra or missing chromosome is a common cause of some genetic disorders. Some cancer cells also have abnormal numbers of chromosomes. About 68% of human solid tumors are aneuploid. Aneuploidy originates during cell division when the chromosomes do not separate properly between the two cells (nondisjunction). Most cases of aneuploidy in the autosomes result in miscarriage, and the most common extra autosomal chromosomes among live births are 21, 18 and 13. Chromosome abnormalities are detected in 1 of 160 live human births. Autosomal aneuploidy is more dangerous than sex chromosome aneuploidy, as autosomal aneuploidy is almost always lethal to embryos that cease develo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cubic Crystal System
In crystallography, the cubic (or isometric) crystal system is a crystal system where the Crystal_structure#Unit_cell, unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. There are three main varieties of these crystals: *Primitive cubic (abbreviated ''cP'' and alternatively called simple cubic) *Body-centered cubic (abbreviated ''cI'' or bcc) *Face-centered cubic (abbreviated ''cF'' or fcc, and alternatively called Close-packing_of_equal_spheres, ''cubic close-packed'' or ccp) Each is subdivided into other variants listed below. Although the ''unit cells'' in these crystals are conventionally taken to be cubes, the primitive_cell, primitive unit cells often are not. Bravais lattices The three Bravais lattices in the cubic crystal system are: The primitive cubic lattice (cP) consists of one Lattice_(group), lattice point on each corner of the cube; this means each simple cubic unit cell has in total one latt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agar
Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from ogonori (''Gracilaria'') and "tengusa" (''Gelidiaceae''). As found in nature, agar is a mixture of two components, the linear polysaccharide agarose and a heterogeneous mixture of smaller molecules called agaropectin. It forms the supporting structure in the cell walls of certain species of algae and is released on boiling. These algae are known as agarophytes, belonging to the Rhodophyta (red algae) phylum. The processing of food-grade agar removes the agaropectin, and the commercial product is essentially pure agarose. Agar has been used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture media for microbiological work. Agar can be used as a laxative; an appetite suppressant; a vegan substitute for gelatin; a thickener for soups; in fruit preserves, ice cream, and other desser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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