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(yo͞okâr`ē-ōt'), a cell or organism composed of cells that have a membrane-bound nucleus and organelles (mitochondria, chloroplasts; see cellcell,
in biology, the unit of structure and function of which all plants and animals are composed. The cell is the smallest unit in the living organism that is capable of integrating the essential life processes. There are many unicellular organisms, e.g.
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, in biology) and genetic material organized in chromosomes in which the DNA is combined with histonehistone
, any of a class of protein molecules found in the chromosomes of eukaryotic cells. They complex with the DNA (see nucleic acid) and pack the DNA into tight masses of chromatin, which have the structure of coiled coils, much like a tangled telephone cord.
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 proteins. Eukaryotes are contrasted with the prokaryotes (see MoneraMonera,
taxonomic kingdom that comprises the prokaryotes (bacteria and cyanobacteria). Prokaryotes are single-celled organisms that lack a membrane-bound nucleus and usually lack membrane-bound organelles (mitochondria, chloroplasts; see cell, in biology).
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). Eukaryotes formed through the merger of prokaryotes, which predate them in the fossil record by some 2 billion years. In the five-kingdom system of classificationclassification,
in biology, the systematic categorization of organisms into a coherent scheme. The original purpose of biological classification, or systematics, was to organize the vast number of known plants and animals into categories that could be named, remembered, and
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, the eukaryotes have comprised the taxonomic kingdoms ProtistaProtista
or Protoctista
, in the five-kingdom system of classification, a kingdom comprising a variety of unicellular and some simple multinuclear and multicellular eukaryotic organisms.
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, FungiFungi
, kingdom of heterotrophic single-celled, multinucleated, or multicellular organisms, including yeasts, molds, and mushrooms. The organisms live as parasites, symbionts, or saprobes (see saprophyte).
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, Plantae (see plantplant,
any organism of the plant kingdom, as opposed to one of the animal kingdom or of the kingdoms Fungi, Protista, or Monera in the five-kingdom system of classification.
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), and Animalia (see animalanimal,
any member of the animal kingdom (kingdom Animalia), as distinguished from organisms of the plant kingdom (kingdom Plantae) and the kingdoms Fungi, Protista, and Monera in the five-kingdom system of classification.
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). In a recently proposed system they are called the eukarya and classified as an overarching group (domain) above the kingdom level.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a single- and multiple-celled plant and animal organism in which the body of the cell, in contrast to the cells of a prokaryote, is differentiated into the cytoplasm and the nucleus enclosed by a membrane. The most recent system of the organic kingdom gives the eukaryotes the rank of a superkingdom (including the animal, mushroom, and plant kingdoms) and juxtaposes them to the superkingdom of the prokaryotes.

The genetic material of the nucleus of eukaryotes is organized into chromosomes that are capable of duplication and distribution through mitosis between daughter cells. The molecular basis of the chromosomes is deoxyribonucleic acid (DNA), which is closely associated with histones and other proteins. In most eukaryotes there is a typical sexual process, with the fusion of cell nuclei during fertilization and reduction division during meiosis. The cytoplasm of the cells of eukaryotes, in contrast to that of prokaryote cells, has a complex system of membranes that form an endoplasmotic network, the Golgi apparatus, the mitochondria, and other organoids.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A cell with a definitive nucleus. Also spelled eucaryote.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
(133) Heerey J held that the claim to the product of procaryotic or eucaryotic expression of an exogenous DNA sequence was permissibly wide because the DNA sequence for EPO was a principle of general application and, therefore, it was acceptable for the claim to be made in correspondingly general terms.
The origin of the chromosome, of the bounded cell, of organized meiosis, diploidy and sex, of the eucaryotic cell, of multicellularity, of gastrulation, of molluscan torsion, of segmentation - each of these may have constituted a watershed event in the history of life.
I never observed cannibalism or the ingestion of eucaryotic competitors by my flagellates.
Many proteins from eucaryotic organisms cannot be synthesized in bacteria (such as E.
Mycoplasmas may be the only procaryotes which can symbiotically grow in the eucaryotic host and have a close interaction with mammalian cells for long periods.
Kozak, "Effects of intercistronic length on the efficiency of reinitiation by eucaryotic ribosomes," Molecular and Cellular Biology, vol.
He started his research career in 1984 with studies on the structural characterization of antigenic polysaccharides obtained from pathogenic eucaryotic microbe, mainly genus Candida, after graduating from the Tohoku Pharmaceutical University, Sendai, Japan.
In 2003, Kozak (Marilyn, 1980) analyzed the relationship between sequence of mRNA 5' end and translation efficiency in the eucaryotic expression gene and found that 5' G/N-C/N-C/N-ANNATGG 3'sequence could improve transcription and translation efficiency, especially A in -3 site and G in +4 site were important to improve the translation efficiency.
Experiments to assess the cytotoxicity of propolis extracts for cultured eucaryotic cells indicate a moderate toxic behaviour of these extracts in cell cultures.
Endoproteolytic Processing of pro-BACE by Members of the Family of Eucaryotic, Subtilisin-Like Endoproteases.
Site of action of a Vero toxin (VT2) from Escherichia coli 0157:H7 and of Shiga toxin on eucaryotic ribosomes.