Differences Between Eukaryotic and Prokaryotic Cells — AQA GCSE Biology

All living things are made of either eukaryotic or prokaryotic cells. Knowing the differences is a common exam requirement.

Eukaryotic cells

• Found in animals, plants, fungi and protists.
• Have a true nucleus that encloses the genetic material (DNA) in a membrane.
• Are generally larger (about 10–100 µm).
• Contain membrane-bound organelles such as mitochondria and (in plants) chloroplasts.

Prokaryotic cells

• Bacteria are prokaryotes.
• Are much smaller (about 1–5 µm).
• Have no nucleus — the genetic material is a single DNA loop floating in the cytoplasm.
• May contain one or more small rings of DNA called plasmids.
• Have a cell wall, cell membrane and cytoplasm but no mitochondria or chloroplasts.

Comparing sizes and orders of magnitude

Prokaryotic cells are roughly 100 times smaller than eukaryotic cells. You should be able to compare sizes using standard form and orders of magnitude, e.g. a bacterium ~1 × 10⁻⁶ m vs an animal cell ~1 × 10⁻⁵ m.

Exam tips

• The key difference: eukaryotic cells have a nucleus; prokaryotic cells do not.
• Learn that bacterial DNA is a single loop, plus plasmids.
• Be able to compare cell sizes using standard form and orders of magnitude.
• Remember prokaryotes are smaller and simpler than eukaryotes.