1.2.5—Prokaryotic cell features (bacteria)

A prokaryote is a unicellular cell whose genetic material is not enclosed in a nucleus and whose cytoplasm has no double-membrane organelles.

The syllabus feature hierarchy is:

• Size: typically 1–5 µm in diameter.
• Cell wall: made of peptidoglycan.
• DNA: a circular DNA molecule lies in the cytoplasm rather than inside a nucleus.
• Ribosomes: 70S ribosomes are present for protein synthesis.
• Organelles: double-membrane organelles such as a nucleus or mitochondrion are absent.

This compact organisation distinguishes a bacterial cell from a eukaryotic cell: the DNA is not separated into a nuclear compartment, and respiration or other processes are not housed in double-membrane organelles. Size supports recognition, but the structural features provide the stronger identification.

No nucleus does not mean no DNA, and a cell wall does not by itself prove that a cell is prokaryotic. Do not add a capsule, flagellum or plasmid to every bacterium: those features are not universal requirements of this objective.