eukaryote
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- The University of Hawaiʻi Pressbooks - Biology - Eukaryotic Cells
- National Center for Biotechnology Information - PubMed Central - The origin and early evolution of eukaryotes in the light of phylogenomics
- Nature - Eukaryotic Cells
- The George Washington University - Eukaryotes
- BCcampus Publishing - Eukaryotic Cells
- Frontiers - The origin of eukaryotes and rise in complexity were synchronous with the rise in oxygen
- Georgia Tech Biological Sciences - Organismal Biology - Eukaryotes and their Origins
- Open Oregon Educational Resources - The Eukaryotic Cell Cycle
- Biology LibreTexts - Eukaryotes
eukaryote, any cell or organism that possesses a clearly defined nucleus. The eukaryotic cell has a nuclear membrane that surrounds the nucleus, in which the well-defined chromosomes (bodies containing the hereditary material) are located. Eukaryotic cells also contain organelles, including mitochondria (cellular energy exchangers), a Golgi apparatus (secretory device), an endoplasmic reticulum (a canal-like system of membranes within the cell), and lysosomes (digestive apparatus within many cell types). There are several exceptions to this, however; for example, the absence of mitochondria and a nucleus in red blood cells and the lack of mitochondria in the oxymonad Monocercomonoides species.
Eukaryotes are thought to have evolved between about 1.7 billion and 1.9 billion years ago. The earliest known microfossils resembling eukaryotic organisms date to approximately 1.8 billion years ago. Compare prokaryote.