ploidy

ploidy
/ploy"dee/, n. Biol.
the number of homologous chromosome sets present in a cell or organism.
[1935-40; see -PLOID, -Y3]

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Number of sets of chromosomes in the nucleus of a cell.

In normal human body cells, chromosomes exist in pairs, a condition called diploidy. During meiosis the cell produces sex cells (gametes), each containing half the normal number of chromosomes, a condition called haploidy. When an egg and a sperm unite in fertilization, the diploid condition is restored. Polyploid cells have three or more times the number of chromosomes found in haploid cells; polyploid organisms usually cannot reproduce. Aneuploid cells have an abnormal number of chromosomes that is not a multiple of the haploid number. Aneuploidy is most often caused by an error leading to an unequal distribution of chromosomes during division.

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      in genetics, the number of chromosomes occurring in the nucleus of a cell. In normal somatic (body) cells, the chromosomes exist in pairs. The condition is called diploidy. During meiosis the cell produces gametes, or germ cells, each containing half the normal or somatic number of chromosomes. This condition is called haploidy. When two germ cells (e.g., egg and sperm) unite, the diploid condition is restored.

       polyploidy refers to cells the nuclei of which have three or more times the number of chromosomes found in haploid cells. This condition frequently occurs in plants and may result from chromosome duplication without division of the cytoplasm or from the union of two diploid gametes. Polyploid animals, because they have more than the normal number of sex chromosomes, are usually sterile.

      Some cells have an abnormal number of chromosomes that is not a whole multiple of the haploid number. This condition, called aneuploidy, is most often caused by some error resulting in an unequal distribution of chromosomes to the daughter cells. Organisms in which aneuploidy occurs may deviate noticeably from the norm in appearance and behaviour.

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Universalium. 2010.

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Look at other dictionaries:

  • ploidy — ploidy. См. плоидность. (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.

  • ploidy — [ploi′dē] n. [ PLOID + Y3] the number of chromosome sets in a nucleus …   English World dictionary

  • -ploidy — n combining form • • • Main Entry: ↑ ploid …   Useful english dictionary

  • Ploidy — Haplo redirects here. For the fictional character, see The Death Gate Cycle. For the aquarium fishes, see Haplochromini. Diploid cells have two homologous copies of each chromosome. Ploidy is the number of sets of chromosomes in a biological cell …   Wikipedia

  • ploidy — The number of haploid sets in a cell. Gametes normally contain one; somatic cells two. SEE ALSO: polyploidy. [ ploid + y, condition] * * * ploi·dy plȯid ē n, pl ploi·dies degree of repetition of the basic number of chromosomes * * * n …   Medical dictionary

  • ploidy — n. the condition of having multiple the normal number of chromosomes for the species. An increase in ploidy in the cells of a malignant tumour usually indicates greater aggressiveness and ability to invade …   The new mediacal dictionary

  • ploidy — ploidiškumas statusas T sritis augalininkystė apibrėžtis Haploidinių organizmo chromosomų rinkinių skaičius. atitikmenys: angl. ploidy rus. плоидность …   Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

  • ploidy — noun Etymology: from such words as diploidy, hexaploidy Date: 1939 degree of repetition of the basic number of chromosomes …   New Collegiate Dictionary

  • ploidy — n. [Gr. aploos, onefold; edios, like] A term referring to the number of chromosome sets …   Dictionary of invertebrate zoology

  • ploidy — noun The number of homologous sets of chromosomes in a cell …   Wiktionary

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