macronucleus

[mak-roh-noo-klee-uhs, -nyoo-]
noun Biology.
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:
1890–95; < Neo-Latin; see macro-, nucleus

macronuclear, adjective
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World English Dictionary
macronucleus (ˌmækrəʊˈnjuːklɪəs)
 
n , pl -clei
Compare micronucleus the larger of the two nuclei in ciliated protozoans

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Medical Dictionary

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 Britannica
Encyclopedia

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.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
Ich's large size and horseshoe-shaped macronucleus are it's best identifying features.
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