macronucleus

American  

[mak-roh-noo-klee-uhs, -nyoo-] / ˌmæk roʊˈnu kli əs, -ˈnyu- /

noun

Biology.

1. the larger of the two types of nuclei nucleus occurring in ciliate protozoans, having a multiple set of chromosomes and functioning in cell metabolism and protein synthesis.

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macronucleus British  

/ ˌmækrəʊˈnjuːklɪəs /

noun

1. the larger of the two nuclei in ciliated protozoans Compare micronucleus

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Other Word Forms

• macronuclear adjective

Etymology

Origin of macronucleus

From New Latin, dating back to 1890–95; macro-, nucleus

Example Sentences

The micronucleus is essential for sexual reproduction, whereas the macronucleus directs asexual binary fission and all other biological functions.

From Textbooks • Jan. 1, 2015

Each Paramecium has a macronucleus and a micronucleus.

From Textbooks • Jan. 1, 2015

The clear spot to the right is the macronucleus, and the blobs are probably storage granules of some sort.

From Scientific American • Oct. 17, 2013

For certain genetic parasites having a useful role in building the macronucleus, see Nowacki, M. et al.

From New York Times • Feb. 10, 2010

The contractile vacuole is central and dorsal; the macronucleus is in the anterior half of the body, with one attached micronucleus.

From Marine Protozoa from Woods Hole Bulletin of the United States Fish Commission 21:415-468, 1901 by Calkins, Gary N. (Gary Nathan)