Prokaryotic Cells

This lesson covers:

  1. The structure of prokaryotic cells 
  2. The functions of their cell parts 
  3. The similarities and differences between eukaryotes and prokaryotes 

Prokaryotes

Prokaryotes are single-celled organisms, so consist of a single prokaryotic cell. These cells are much smaller than eukaryotic cells and do not contain a nucleus or other membrane-bound organelles. 

The diagram below shows the basic structure of a prokaryotic cell.

Diagram showing the basic structure of a prokaryotic cell with labels for cell surface membrane, cell wall, ribosomes, DNA, and plasmids.

How prokaryotic cells differ from eukaryotic cells:

  • Cell well - In prokaryotic cells, this is made of murein (pepdidoglycan).
  • Ribosomes - Prokaryotic cells have 70S ribosomes, which are smaller than the 80S ribosomes found in eukaryotic cells.
  • Genetic material - In prokaryotic cells, this is mostly found in a large circular strand of DNA (sometimes called a circular chromosome or nucleoid), and some extra genes (like those for antibiotics resistance) are found in smaller loops called plasmids.

Prokaryotic organelles

Prokaryotic cells may also contain additional organelles such as capsules, flagella and pili. 

Illustration of a prokaryotic cell showing the capsule, flagella, and pili organelles.

Some prokaryotes (e.g. bacteria) have an extra layer around the cell wall known as a capsule.


This structure is made up of polysaccharides and protects the cells from attack by antibiotics or white blood cells.

Comparing eukaryotes and prokaryotes

Table comparing features of eukaryotes and prokaryotes including cell type, size, DNA, ribosomes, organelles, and cell wall.