---
title: "Prokaryotic and Eukaryotic Cells"
description: "Compare a bacterial cell with plant and animal cells: a free loop of DNA and plasmids on one side, a nucleus and membrane-bound organelles on the other. Sets the size scale the rest of cell biology wo"
canonical: https://lightmysky.com/learn/science/prokaryotic-and-eukaryotic-cells-mt_vlL4GinuH6
source: https://lightmysky.com/learn/science/prokaryotic-and-eukaryotic-cells-mt_vlL4GinuH6.md
retrieved: 2026-09-12
---

> **Agent view.** This is the Markdown twin of the page, for tools and assistants.
> When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md
> API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md
> Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt
> Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json
> Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`.

# Prokaryotic and Eukaryotic Cells

Compare a bacterial cell with plant and animal cells: a free loop of DNA and plasmids on one side, a nucleus and membrane-bound organelles on the other. Sets the size scale the rest of cell biology works in.

Subject: Science · Area: Organisms & Life Processes · Ages 14 to 15
Page: https://lightmysky.com/learn/science/prokaryotic-and-eukaryotic-cells-mt_vlL4GinuH6

## Ready when they can

- Names the parts a bacterial cell has and the parts it does not, and says which structures a plant cell adds to the animal set.
- Places a bacterium, an animal cell and a plant cell in size order using micrometres.
- Says why plasmids matter to a bacterium even though they sit outside the main chromosome.

## Lesson: Two kinds of cells

Cells fall into two broad groups. Prokaryotes are mostly single-celled organisms of the Bacteria and Archaea domains. They have no nucleus and no membrane-bound organelles. Their DNA sits as a free loop in a central nucleoid, plus small rings called plasmids.

**Example.** Animals, plants, fungi, and protists are all eukaryotes. Their DNA is locked inside a true nucleus, and the cell carries specialised organelles: mitochondria release energy, ribosomes build proteins, membranes control traffic. A plant cell then adds three things animals lack: a wall, chloroplasts, and a big vacuole.

Size tells the same story. All cells share a membrane, cytoplasm, DNA, and ribosomes, but bacteria are about ten times smaller than animal cells, measured in micrometres. Microscopes reveal the gap: stain, magnify, and compare the micrographs.

**Tip.** Remember plasmids even though they sit outside the main chromosome. They are small DNA rings swapped between bacteria, often carrying antibiotic resistance. That swap is why they matter far beyond their size.

**Recap.** Bacteria carry a free DNA loop without a nucleus, while plant and animal cells lock DNA in one.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Parts of Plant and Animal Cells](https://lightmysky.com/learn/science/parts-of-plant-and-animal-cells-mt_bABr-c2DfV)
- [Cells Under the Microscope](https://lightmysky.com/learn/science/cells-under-the-microscope-mt_VfA4xo4kUv)

## Opens up

- [Magnification and Scale Calculations](https://lightmysky.com/learn/science/magnification-and-scale-calculations-mt_0Iowx29ddQ)
- [Protists: The Eukaryotes That Are Not Plants, Animals or Fungi](https://lightmysky.com/learn/science/protists-the-eukaryotes-that-are-not-plants-animals-or-fungi-mt_CHb8H727nW)
- [Bacterial Cell Envelopes and What the Gram Stain Reveals](https://lightmysky.com/learn/science/bacterial-cell-envelopes-and-what-the-gram-stain-reveals-mt_Q5zM0oO3Vu)