What is "eukaryote"

eukaryote \eukaryote\ n. an organism with "good" or membrane-bound nuclei having multiple chromosomes; eucaryotes also have other membrane-bound organelles such as mitochondria or chloroplasts, within the cytoplasm enclosed by the outer membrane. Such cells are characteristic of all life forms except primitive microorganisms such as bacteria and blue-green algae. Contrasted with prokaryote.

Syn: eucaryote.

n. Any of the single-celled or multicellular organisms, of the taxonomic domain ''Eukaryota'', whose cells contain at least one distinct nucleus.

n. an organism with cells characteristic of all life forms except primitive microorganisms such as bacteria; i.e. an organism with `good' or membrane-bound nuclei in its cells [syn: eucaryote] [ant: prokaryote]

A eukaryote ( or or ) is any organism whose cells contain a nucleus and other organelles enclosed within membranes.

Eukaryotes belong to the taxon Eukarya or Eukaryota. The defining feature that sets eukaryotic cells apart from prokaryotic cells ( Bacteria and Archaea) is that they have membrane-bound organelles, especially the nucleus, which contains the genetic material, and is enclosed by the nuclear envelope. The presence of a nucleus gives eukaryotes their name, which comes from the Greek εὖ (eu, "well") and κάρυον (karyon, "nut" or "kernel"). Eukaryotic cells also contain other membrane-bound organelles such as mitochondria and the Golgi apparatus. In addition, plants and algae contain chloroplasts. Eukaryotic organisms may be unicellular, or multicellular. Only eukaryotes form multicellular organisms consisting of many kinds of tissue made up of different cell types.

Eukaryotes can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion. In mitosis, one cell divides to produce two genetically identical cells. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells each with half the number of chromosomes as the original parent cell ( haploid cells). These act as sex cells ( gametes – each gamete has just one complement of chromosomes, each a unique mix of the corresponding pair of parental chromosomes) resulting from genetic recombination during meiosis.

The domain Eukaryota appears to be monophyletic, and so makes up one of the three domains of life. The two other domains, Bacteria and Archaea, are prokaryotes and have none of the above features. Eukaryotes represent a tiny minority of all living things. However, due to their much larger size, eukaryotes' collective worldwide biomass is estimated at about equal to that of prokaryotes. Eukaryotes first developed approximately 1.6–2.1 billion years ago (during the proterozoic eon).