eukaryote
- Key People:
- Lynn Margulis
- Susan L. Lindquist
- Roger D. Kornberg
- Related Topics:
- cell
- prokaryote
- living things
- On the Web:
- Khan Academy - Prokaryotic and eukaryotic cells (Apr. 08, 2025)
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.
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How do eukaryotic cells differ from prokaryotic cells?
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What are organelles and what functions do they perform in a cell?
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How did eukaryotic cells evolve from prokaryotic cells?
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What are chromosomes and why are they important?
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Why do some eukaryotic cells like red blood cells lack a nucleus?
