chromosome number

the characteristic number of chromosomes contained in the cell nucleus of a given species.

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      precise number of chromosomes typical for a given species. In any given asexually reproducing species, the chromosome number is always the same. In sexually reproducing organisms, the number of chromosomes in the body (somatic) cells is diploid (2n; a pair of each chromosome), twice the haploid (1n) number found in the sex cells, or gametes. The haploid number is produced during meiosis (q.v.). An organism with any multiple of the diploid number of chromosomes is said to be polyploid. Although it is a normal evolutionary strategy among many plant groups, polyploidy is frequently linked to abnormalities in animals. Any change from the typical chromosome number for a species may be accompanied by changes—sometimes drastic—in the organism. The number of chromosomes does not correlate with the apparent complexity of an animal or plant: in human beings, for example, the diploid number is 2n = 46 (that is, 23 pairs), compared with 2n = 78, or 39 pairs, in the dog and 2n = 36 (18) in the common earthworm. There is an equally great range of numbers among plants.

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Universalium. 2010.

Look at other dictionaries:

  • chromosome number — n the usu. constant number of chromosomes characteristic of a particular kind of animal or plant * * * the number of chromosomes present in the somatic cells of an organism; the normal individual receives, at conception, one set of chromosomes… …   Medical dictionary

  • chromosome number — chromosome number. См. хромосомное число. (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.

  • chromosome number — /ˈkroʊməsoʊm nʌmbə/ (say krohmuhsohm numbuh) noun the characteristic number of chromosomes for each biological species. In sex cells this number is haploid; in fertilised eggs it is diploid, one half coming from the egg, one half from the sperm.… …   Australian English dictionary

  • chromosome number — noun Date: 1910 the usually constant number of chromosomes characteristic of a particular kind of animal or plant …   New Collegiate Dictionary

  • chromosome number — noun : the number of chromosomes characteristic of a particular kind of plant or animal …   Useful english dictionary

  • Chromosome — For a non technical introduction to the topic, see Introduction to genetics. Diagram of a replicated and condensed metaphase eukaryotic chromosome. (1) Chromatid – one of the two identical parts of the chromosome after S phase. (2)… …   Wikipedia

  • chromosome — chromosomal, adj. chromosomally, adv. /kroh meuh sohm /, n. Genetics. any of several threadlike bodies, consisting of chromatin, that carry the genes in a linear order: the human species has 23 pairs, designated 1 to 22 in order of decreasing… …   Universalium

  • Chromosome — A visible carrier of the genetic information. The 3 billion bp (base pairs) in the human genome are organized into 24 distinct, physically separate microscopic units called chromosomes. All genes are arranged linearly along the chromosomes. The… …   Medical dictionary

  • chromosome — Synonyms and related words: Altmann theory, DNA, De Vries theory, Galtonian theory, Mendelianism, Mendelism, RNA, Verworn theory, W chromosome, Weismann theory, Weismannism, Wiesner theory, X chromosome, Y chromosome, Z chromosome, accessory… …   Moby Thesaurus

  • chromosome aberration — In a broad sense, all types of changes in chromosome structure and chromosome number …   Dictionary of invertebrate zoology

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