Eukaryotes and prokaryotes

Bacteria are amongst the simplest of organisms – they are made of single cells. Their cell structure is simpler than the cells of animals, plants and fungi.

  • Cells of animals, plants and fungi are called eukaryotic cells.
  • Cells of bacteria are called prokaryotic cells.
Three different cells - a plant cell, a bacteria cell and an animal cellDiagram not to scale. Prokaryotic cells are smaller than eukaryotic ones

Cells of bacteria do not have a nucleus. Their DNA is present in the cytoplasm of their cells. It is found in a loop. Bacteria can also have much smaller circles of DNA called plasmids. These are able to move from one cell to another. They provide genetic variation.

Comparing cell types

Eukaryotic cellProkaryotic cell
SizeMost are 5 μm – 100 μmMost are 0.2 μm – 2.0 μm
Outer layers of cellCell membrane - surrounded by cell wall in plants and fungiCell membrane - surrounded by cell wall
Cell contentsCytoplasm, cell organelles include mitochondria, chloroplasts in plants, and ribosomesCytoplasm, ribosomes - no mitochondria or chloroplasts
Genetic materialDNA in a nucleus - plasmids are found in a few simple eukaryotic organismsDNA is a single molecule, found free in the cytoplasm - additional DNA is found on one or more rings called plasmids
Type of cell divisionMitosisBinary fission

A group of organisms called Archaea are also prokaryotic.