Prokaryotes

Bacteria are amongst the simplest of organisms - they are made of single cells. Their cell structure is simpler than the cells of eukaryotes and cells are smaller, most are 0.2 μm - 2.0 μm.

These cells do not contain membrane bound organelles such as a nucleus and mitochondria.

Bacterial cells are called prokaryotic cells.

Diagram of a bacteria cell

Prokaryotes and eukaryotes have some structures in common.

Prokaryotes have features such as:

  • A single loop of DNA free in the cytoplasm
  • An additional circular piece of DNA called a plasmid, used to transfer genetic material from one cell to another

The types of cell compared:

FeatureAnimal cellPlant cellProkaryotic cell
Nucleus×
Cell membrane
Cytoplasm
Cell wall×
Vacuole××
Chloroplasts××
Plasmids××
DNA free in cytoplasm××