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Learn5090Paper 1 · Multiple ChoiceCellsCell structure
Cells · Subtopic 1 of 2

Cell Structure

All living things are made of cells. Animal cells have a cell membrane (controls what enters and leaves), cytoplasm (where reactions happen), a nucleus (contains DNA, controls the cell), mitochondria (aerobic respiration) and ribosomes (protein synthesis). Plant cells also have a cellulose cell wall (support), chloroplasts (photosynthesis) and a large permanent vacuole (cell sap, keeps cells firm). Bacterial cells have no nucleus: their DNA is a single loop, often with plasmids.

Cambridge 5090 Paper 1Cambridge 5090 Paper 2Cambridge 0610 Papers 2, 4Cambridge 0610 Papers 1, 3Edexcel 4BI1 Paper 1BEdexcel 4BI1 Paper 2B≈ 35 minRevision 1 · updated 2026-10-30
Section 1 of 14

Learning objectives

  • Identify structures in animal, plant and bacterial cells.
  • State the function of each structure.
  • Compare plant, animal and bacterial cells.
Pause and think

A potato is a plant, but potato cells have no chloroplasts. Why?

Section 2 of 14

Core idea

Start hereThirty trillion tiny factories

You are made of about 30 trillion cells. Each one has its own control centre, power stations and protein factories, all packed into a space too small to see.

The big idea

Every cell has a membrane, cytoplasm and ribosomes. Animal and plant cells also have a nucleus and mitochondria; plants add a wall, chloroplasts and a vacuole. Bacteria have no nucleus.

1. What's in a cell

Comparing cell types

Shared structures first, then the extras.

Worked exampleIdentify from a description

A cell has a nucleus, a large vacuole and a cellulose wall, but no chloroplasts.

Goal
Where could it come from?
Strategy
Wall + vacuole = plant; no chloroplasts = no light.
  1. cellulose wall⇒plant\text{cellulose wall}\Rightarrow\text{plant}
    Only plant cells have cellulose walls.
  2. no chloroplasts⇒not photosynthesising\text{no chloroplasts}\Rightarrow\text{not photosynthesising}
    Probably underground or inside the stem.
AnswerA plant root cell.
✓ CheckRoot cells live in the dark ✓.
Key takeawayFunctions in brief Membrane: controls entry and exit. Nucleus: genetic information. Mitochondria: aerobic respiration. Ribosomes: protein synthesis. Chloroplasts: photosynthesis. Wall: support. Vacuole: cell sap, turgor.
Pause and think

Why do liver cells have lots of ribosomes?

Summary

  • Plant extras: wall, chloroplasts, vacuole.
  • Bacteria: no nucleus.
  • Structure → function.
Key words
Organelle
A structure inside a cell with a specific job.
Plasmid
Small ring of DNA in bacteria.
Partially permeable
Lets some substances through but not others.
HistoryRobert Hooke. In 1665 Robert Hooke looked at cork under a microscope and saw tiny boxes. He called them "cells" because they reminded him of monks' small rooms.
Fun factMore bacteria than you. Your body contains roughly as many bacterial cells as human cells: around 38 trillion, mostly in your gut.
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