polyploidy


polyploidy

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      the condition in which a normally diploid cell or organism acquires one or more additional sets of chromosomes. In other words, the polyploid cell or organism has three or more times the haploid chromosome number. Polyploidy arises as the result of total nondisjunction of chromosomes during mitosis or meiosis.

      Polyploidy is common among plants and has been, in fact, a major source of speciation in the angiosperms. Particularly important is allopolyploidy, which involves the doubling of chromosomes in a hybrid plant. Normally a hybrid is sterile because it does not have the required homologous pairs of chromosomes for successful gamete formation during meiosis. If through polyploidy, however, the plant duplicates the chromosome set inherited from each parent, meiosis can occur, because each chromosome will have a homologue derived from its duplicate set. Thus, polyploidy confers fertility on the formerly sterile hybrid, which thereby attains the status of a full species distinct from either of its parents. It has been estimated that up to half of the known angiosperm species arose through polyploidy, including some of the species most prized by man. Plant breeders utilize this process, treating desirable hybrids with chemicals, such as colchicine, that are known to induce polyploidy.

      Polyploid animals are far less common, and the process appears to have had little effect on animal speciation.

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Universalium. 2010.

Look at other dictionaries:

  • Polyploidy — occurs in cells and organisms when there are more than two homologous sets of chromosomes.Most organisms are normally diploid; polyploidy may occur due to abnormal cell division. It is most commonly found in plants. Haploidy may also occur as a… …   Wikipedia

  • polyploidy — polyploidy. См. полиплоидия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • polyploidy — (n.) 1922, from Ger. polyploidie (1910), from polyploid, from Gk. poly (see POLY (Cf. poly )) + ploid (comb. form of ploos fold + OID (Cf. oid)) …   Etymology dictionary

  • polyploidy — poliploidija statusas T sritis ekologija ir aplinkotyra apibrėžtis Chromosomų rinkinio kartotinis padaugėjimas (padvigubėjimas, patrigubėjimas ir t. t.) ląstelės branduolyje. atitikmenys: angl. polyploidy vok. Polyploidie, f rus. полиплоидия, f …   Ekologijos terminų aiškinamasis žodynas

  • polyploidy — poliploidija statusas T sritis augalininkystė apibrėžtis Pagrindinio chromosomų skaičiaus branduolyje padidėjimas trimis, keturiais, penkiais chromosomų rinkiniais ar daugiau. atitikmenys: angl. polyploidy rus. полиплоидия …   Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

  • polyploidy — noun see polyploid …   New Collegiate Dictionary

  • polyploidy — n. [Gr. polys, many; aploos, onefold] A condition in which the chromosome sets in the nucleus are a multiple of the normal diploid number …   Dictionary of invertebrate zoology

  • polyploidy — noun the state or condition of being a polyploid; having more than the usual number of complete sets of chromosomes See Also: ploidy …   Wiktionary

  • polyploidy — The state of a cell nucleus containing three or more haploid sets. Cells containing three, four, five, or six multiples are referred to, respectively, as triploid, tetraploid, pentaploid, or hexaploid. [poly + G. ploides, in form] * * *… …   Medical dictionary

  • polyploidy — pÉ‘lɪplɔɪdɪ / pÉ’l n. (Biology) state of having three or more times the normal number of chromosomes (about cells) …   English contemporary dictionary


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