Bacterial cells

Organisation of the organism · Cell structure · note 2 of 4

Spec 2.1.2, 2.1.3, 2.1.4Download all Cell structure notes (PDF)Download all notes (PDF)6 pages

Bacterial cellsSpec 2.1.2, 2.1.3, 2.1.4

In short

A bacterial cell is a simple cell with a cell wall, cell membrane, cytoplasm and ribosomes but no nucleus. Its genetic material is a single loop of circular DNA lying free in the cytoplasm, and it may also have plasmids, which are small rings of extra DNA. Its cell wall is not made of cellulose.

A bacterial cell is much simpler than a plant or animal cell. It has no nucleus. Its genetic material is a single loop of circular DNA that lies free in the cytoplasm. Bacteria may also have one or more small rings of extra DNA called plasmids.

Structures in a bacterial cell
Structure	Function
Cell wall	Surrounds the cell and gives it strength and shape (not made of cellulose)
Cell membrane	Controls the movement of substances into and out of the cell
Cytoplasm	Where chemical reactions happen
Ribosomes	Make proteins (protein synthesis)
Circular DNA	Contains the genetic material; controls the activities of the cell
Plasmids	Small rings of extra DNA that carry a few additional genes

A rod-shaped bacterial cell labelled with cell wall, cell membrane, cytoplasm, ribosomes, circular DNA lying free in the cytoplasm and a plasmid. — A bacterial cell has no nucleus: its circular DNA lies free in the cytoplasm.

Exam tip:

Write 'circular DNA free in the cytoplasm' rather than 'no DNA'. Bacteria do have DNA. What they lack is a nucleus to hold it.

Written and checked against the Cambridge IGCSE Biology (0610) specification · Updated October 2026

Frequently asked questions

What is the difference between plant and animal cells?

Plant cells have a cellulose cell wall, chloroplasts and a large vacuole containing cell sap, which animal cells do not have. Both types of cell have a cell membrane, cytoplasm, a nucleus, ribosomes and mitochondria. In an exam, name a structure only one cell has, for example 'plant cells have a cell wall, animal cells do not'.

Why do plant cells have a cell wall?

Plant cells have a cell wall because it strengthens the cell and supports it. The wall is made of cellulose and is fully permeable, so it does not control what enters the cell; that is the job of the cell membrane. The large vacuole of cell sap also helps keep the cell firm.

What is the difference between a bacterial cell and a plant cell?

A bacterial cell has no nucleus, chloroplasts or large vacuole. Its DNA is a single circular loop free in the cytoplasm, often with extra rings called plasmids. Like a plant cell, it has a cell wall, cell membrane, cytoplasm and ribosomes, but the bacterial cell wall is not made of cellulose.

All 5 questions on Cell structure