Whittaker [R. H.] & Margulis [L.]
Whittaker & Margulis
The domain Eukaryota or Eukarya appears to be monophyletic, and so makes up one of the three domains of life.
The two other domains, Bacteria and Archaea, are prokaryotes. Eukaryotic cells have a nucleus which is a membrane structure containing the genetic material. Eukaryotic cells also contain other membrane-bound organelles such as mitochondria and the Golgi apparatus. All multicellular organisms are eukaryotes, including animals, plants and fungi. Eukaryotes have two types of cell division processes.
In mitosis, one cell divides to produce two genetically identical cells. In meiosis, which is required in sexual reproduction, one diploid cell (having two instances of each chromosome, one from each parent) undergoes recombination of each pair of parental chromosomes, and then two stages of cell division, resulting in four haploid cells (gametes). Each gamete has just one complement of chromosomes, each a unique mix of the corresponding pair of parental chromosomes.
Eukaryotes first developed approximately 1.6–2.1 billion years ago.
2018 01 01 - 00:00