Short answer
Prokaryotes are cellular organisms without a membrane-bound nucleus; bacteria and archaea belong here. Eukaryotes have cells with a nucleus and membrane-bound organelles; animals, plants and fungi belong here. Both have DNA, ribosomes and cell membranes. 1 2
Two broad cellular organizations distinguished primarily by a membrane-bound nucleus and associated internal structure.
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At a glance
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| Question | Prokaryote | Eukaryote |
|---|---|---|
| Nucleus | No membrane-bound nucleus | Membrane-bound nucleus |
| Typical members | Bacteria and archaea | Animals, plants, fungi and protists |
| DNA location | Nucleoid region | Usually nucleus, with organelle DNA in some cells |
The table summarizes the cited definitions and the article’s stated scope. 1 2
What each thing is
Prokaryote. An organism whose cells lack a membrane-bound nucleus; bacteria and archaea are prokaryotic. 1
Eukaryote. An organism whose cells have a membrane-bound nucleus and other internal compartments. 2
Key differences
The dividing feature is cell organization, not whether the organism is “simple” or “advanced.” Eukaryotic cells generally have compartmentalized structures such as mitochondria. Prokaryotic cells can have intricate metabolism and highly diverse forms. 1 2
In a prokaryotic cell, DNA is not sealed in a nuclear compartment. In a eukaryotic cell, the nucleus separates much of the genetic material from the surrounding cytoplasm, while other organelles carry out specialized functions. This organization affects how a cell handles DNA and proteins, but both cell types still perform the basic tasks of life. 1 2
How to tell them apart
In a cell diagram, look for a nucleus enclosed by a membrane. If one is present, eukaryote is the usual classification. If DNA sits in a nucleoid without a nuclear membrane, prokaryote is the usual term. 1 2
Where they overlap
Both are living cellular organisms that store genetic information, make proteins and exchange matter with the environment. Both include microscopic members. 1 2
Edge cases
Some eukaryotic cells, including mature human red blood cells, lose their nucleus; that does not make the organism prokaryotic. Viruses are not classified as either cellular type. Archaea resemble bacteria in lacking a nucleus but form a distinct lineage. 1 2
The labels classify organisms by their cellular ancestry and organization, not by the appearance of every cell at every stage. A mature mammalian red blood cell lacks a nucleus because of its specialized development, yet the animal that produced it remains a eukaryote. “No nucleus in this one cell” is therefore not a complete taxonomy test. 1 2
Why the distinction exists
The categories describe a deep difference in how cells package and manage genetic material. It helps explain major differences in reproduction, cell architecture and some drug targets. 1 2
Common misconceptions
“Prokaryote” is not another word for bacterium. Archaea are prokaryotes too; fungi are eukaryotes even when tiny or single-celled. 1 2
Examples
A common bacterium in soil is a prokaryote; a yeast cell is a eukaryote despite both being microscopic. 1 2
Sources
Sources checked October 3, 2026.
- OpenStax Biology 2e — Prokaryotic Cells. 4.2 Prokaryotic Cells.
- OpenStax Biology 2e — Eukaryotic Cells. 4.3 Eukaryotic Cells.