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macronucleus

[mak-roh-noo-klee-uh s, -nyoo-] /ˌmæk roʊˈnu kli əs, -ˈnyu-/
noun, Biology
1.
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.
Compare micronucleus.
Origin
1890-1895
1890-95; < Neo-Latin; see macro-, nucleus
Related forms
macronuclear, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for macronucleus
  • Ich's large size and horseshoe-shaped macronucleus are it's best identifying features.
British Dictionary definitions for macronucleus

macronucleus

/ˌmækrəʊˈnjuːklɪəs/
noun (pl) -clei (-klɪˌaɪ)
1.
the larger of the two nuclei in ciliated protozoans Compare micronucleus
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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macronucleus in Medicine

macronucleus mac·ro·nu·cle·us (māk'rō-nōō'klē-əs, -nyōō'-)
n.
The larger of two nuclei present in ciliate protozoans, which controls the nonreproductive functions of the cell.


mac'ro·nu'cle·ar adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Encyclopedia Article for macronucleus

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.

Learn more about macronucleus with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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