macronucleus

macronucleus
macronuclear, adj.
/mak'roh nooh"klee euhs, -nyooh"-/, n. Biol.
the larger of the two types of nuclei occurring in ciliate protozoans, having a multiple set of chromosomes and functioning in cell metabolism and protein synthesis. Cf. micronucleus.
[1890-95; < NL; see MACRO-, NUCLEUS]

* * *

      relatively large nucleus believed to influence many cell activities. It occurs in suctorian and ciliate protozoans (e.g., Paramecium). The macronucleus is associated with one or more smaller micronuclei, which are necessary for conjugation and autogamy (reproduction by exchange between the nuclei of different individuals and of the same individuals, respectively). When these reproductive processes occur, the macronucleus degenerates. It is re-formed from nuclear material in the zygote.

* * *


Universalium. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • macronucléus — ● macronucléus nom masculin Le plus gros noyau des protozoaires ciliés, par opposition avec le plus petit, ou micronucléus. macronucleus n. m. BIOL élément constitutif, avec le micronucleus, du noyau des infusoires …   Encyclopédie Universelle

  • macronucleus — macronucleus. См. макронуклеус. (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.

  • macronucleus — [mak΄rō no͞o′klē əs] n. the larger of two types of nuclei present in the cells of ciliated protozoans macronuclear adj …   English World dictionary

  • Macronucleus — A macronucleus (formerly also meganucleus) is the larger type of nucleus in ciliates. Macronuclei are polyploid and undergo direct division without mitosis. It controls the non reproductive cell functions, the everyday tasks, such as metabolism.… …   Wikipedia

  • macronucleus — The larger nucleus (or sometimes nuclei) in ciliate protozoans. Derived from the micronucleus by a process of DNA polytenisation. The DNA in the macronucleus is actively transcribed. The macronucleus degenerates before conjugation …   Dictionary of molecular biology

  • macronucleus — noun The larger the two nuclei present in ciliate protozoans; it controls the nonreproductive functions of the cell. These binucleated forms have one macronucleus functional and another sexual micronucleus which is not functional in the ordinary… …   Wiktionary

  • macronucleus-destined sequences — macronucleus destined sequences. См. предназначенные для макронуклеуса последовательности. (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.

  • macronucleus — noun Etymology: New Latin Date: 1892 a relatively large densely staining nucleus of most ciliate protozoans that is derived from micronuclei and controls various nonreproductive functions • macronuclear adjective …   New Collegiate Dictionary

  • macronucleus — (mak ro nu kle us) The larger of the two nuclei in ciliate protozoa. It is normally polyploid and directs the routine activities of the cell …   Dictionary of microbiology

  • macronucleus — 1. A nucleus that occupies a relatively large portion of the cell, or the larger nucleus where two or more are present in a cell. SYN: meganucleus. 2. The larger of the two nuclei in ciliates, which governs vegetative metabolic functio …   Medical dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”