Plant and animal cells are both eukaryotic cells: each has a nucleus holding its DNA, a cell membrane controlling what enters and leaves, cytoplasm where most chemical reactions happen, mitochondria for aerobic respiration and ribosomes for making proteins. Plant cells have three extra structures. A cellulose cell wall gives them strength and a fixed shape. A large permanent vacuole full of cell sap keeps the cell firm. Chloroplasts, containing chlorophyll, carry out photosynthesis, though only in cells that get light. Animal cells have no cell wall, so they are flexible and often rounded, and they store energy as glycogen rather than starch. Bacteria are simpler again: prokaryotic, with no nucleus.

This guide goes from the GCSE and middle-school version to the A level and AP version. Stop where your course stops.

Every organelle in one table

Read the first eight rows for GCSE. The rest are the A level, IB and AP additions, seen with an electron microscope.

A useful way to learn the table is to follow one protein. The instructions start in the nucleus, the protein is built on a ribosome on the rough ER, packaged in the Golgi apparatus and carried to the membrane in a vesicle, all powered by ATP from mitochondria. That is a scene plan in itself.

What only plant cells have, and why

Each of the three plant-only structures answers one problem plants have and animals do not.

Plants cannot move to find food, so they make it. Chloroplasts capture light and turn carbon dioxide and water into glucose. That is why they appear only where light reaches: palisade cells near the top of a leaf are packed with them, and root hair cells have none. The full chemistry is in photosynthesis, explained visually.

Plants have no skeleton, so they hold themselves up with water pressure. The vacuole fills with water, pushes the cytoplasm against the wall, and the wall pushes back. A cell in that state is turgid. A plant that loses water has flaccid cells and wilts. Put plant cells in strong salt solution and the cytoplasm pulls away from the wall entirely, which is plasmolysis.

Water pressure needs something to push against. The cellulose cell wall is strong enough that a turgid cell does not burst. An animal cell placed in pure water has no wall, so it swells and can burst, which is why red blood cells in pure water split open.

Two consequences examiners like. Plant cells have regular, often box-like shapes because of the wall; animal cells vary. And plants store spare glucose as starch, animals as glycogen (and fat).

Prokaryotic and eukaryotic cells

Plant, animal and fungal cells are eukaryotic. Bacteria are prokaryotic, and much smaller.

The size gap is the one to remember: a typical animal cell is around ten to a hundred times wider than a typical bacterium. A good sentence for a video: "If a bacterium were the size of a grain of rice, your cheek cell would be the size of a dinner plate." That is roughly right, and it makes the scale stick.

Microscopy and magnification

The two kinds of microscope

Magnification is how much bigger the image is. Resolution is how much detail it can show. A blurry photo enlarged ten times is magnified but not better resolved. Electron microscopes matter because of resolution: ribosomes are about 20 to 30 nm across, far below what light can separate. On a light microscope the total magnification is the eyepiece times the objective, so a ×10 eyepiece with a ×40 objective gives ×400.

The formula

magnification = image size ÷ actual size

Rearranged: actual size = image size ÷ magnification, and image size = actual size × magnification. Many students remember it as the triangle "I AM": Image = Actual × Magnification.

The units are where marks go. Both sizes must be in the same unit before you divide.

• 1 millimetre (mm) = 1,000 micrometres (µm)
• 1 micrometre (µm) = 1,000 nanometres (nm)

Two worked examples

Find the actual size. A drawing of a cheek cell is 30 mm wide. The magnification is ×600. How wide is the real cell, in micrometres?

actual size = 30 mm ÷ 600 = 0.05 mm. Convert: 0.05 × 1,000 = 50 µm. That fits: a cheek cell is roughly 50 to 60 µm across.

Find the magnification. An electron micrograph shows a mitochondrion 45 mm long. The real mitochondrion is 3 µm long.

Convert first: 45 mm = 45,000 µm. magnification = 45,000 ÷ 3 = ×15,000. Magnification has no units.

A quick sense check catches most errors. A plant cell is tens of micrometres, a mitochondrion a few micrometres, a bacterium one or two. If your answer says a cheek cell is 50 mm wide, you forgot to convert.

Mistakes that cost the easy marks

• "Plant cells do not have mitochondria." They do. Plants respire all the time, day and night.
• "All plant cells have chloroplasts." Root cells and many cells inside stems do not.
• "The cell wall controls what enters the cell." That is the membrane. The wall is fully permeable and gives strength.
• "The nucleus is the brain of the cell." Fine as a picture, but write "contains genetic material that controls the activities of the cell".
• Saying mitochondria "make energy". Energy cannot be made. They release energy from glucose by respiration.
• Ribosomes drawn as tiny circles on a light-microscope diagram. They are too small to see with a light microscope.
• Bacteria drawn with a nucleus. Draw the DNA as a loose loop in the cytoplasm, with a plasmid or two.
• Forgetting to convert units before using the magnification formula, and giving magnification a unit.
• Biological drawings with shading. Use single clean lines, no shading, label lines that do not cross, and a title with the magnification.

A scene plan for a four minute video

Cells are a comparison topic, so the strongest video builds one cell, then changes it into the other. About 600 words of narration gives four minutes at 150 spoken words a minute.

1. A leaf and a cheek swab side by side. Both are made of cells, and the cells are similar in most ways.
2. Draw an animal cell, adding one structure per sentence: membrane, cytoplasm, nucleus, mitochondria, ribosomes.
3. Follow one protein: nucleus to ribosome to Golgi to the membrane, for A level and AP.
4. Now turn it into a plant cell. Add a cell wall around it, labelled cellulose.
5. Add the vacuole, which swells and pushes the contents against the wall: turgid. Then drain it: flaccid, wilting.
6. Add chloroplasts, and show a root cell with none.
7. Shrink to a bacterium beside the cell for scale: no nucleus, a loop of DNA, plasmids, a flagellum.
8. A microscope, eyepiece times objective, then the cheek cell calculation worked on screen.
9. The comparison table, built row by row, as the final summary.

Building the plant cell on top of the animal cell is the move that does the work. The viewer sees the extra structures arrive one at a time, each with its reason. For more ways to structure a biology video around one changing picture, see how to make a biology explainer video for a school assignment.

Make your own version

1. 1

   Decide your level

   GCSE and middle school need the first eight rows of the table, prokaryotes and magnification. A level, IB and AP add ER, Golgi, lysosomes, ribosome sizes and resolution. Check your specification first.

2. 2

   Write one paragraph per scene

   Follow the scene plan above, one structure and one job per sentence. Use the exact words your mark scheme uses, such as 'controls the activities of the cell'.

3. 3

   Paste the script into openCanviz

   Choose Keep my wording so every term is said as written, set a target length of about four minutes, and pick whiteboard or doodle on paper so the cell builds one part at a time.

4. 4

   Check every label

   Pause on each scene. Drafted drawings can give a plant cell no mitochondria, a bacterium a nucleus, or put chloroplasts in a root cell. Fix any wrong label in the editor for that scene.

5. 5

   Test yourself with it

   Watch once, then pause before each scene and say which structure comes next and what it does. Watching is not revising; recalling is.

If your course has many diagrams like this one, how to study a diagram-heavy subject covers how to learn them by redrawing rather than rereading. The next topic in many courses, how a cell copies its DNA before dividing, is in DNA replication, explained visually.

Common questions

What are the three main differences between plant and animal cells? Plant cells have a cellulose cell wall, a large permanent vacuole and chloroplasts. Animal cells have none of these. Plant cells also store starch, while animal cells store glycogen.

Do animal cells have a vacuole? Not a large permanent one. They can have small, temporary vacuoles and vesicles that move substances around.

Do plant cells have a cell membrane as well as a cell wall? Yes. The membrane sits just inside the wall and controls what enters and leaves. The wall gives strength.

Are fungi plant cells? No. Fungal cells have a cell wall, but it is made of chitin, not cellulose, and they have no chloroplasts.

Why can you not see ribosomes with a light microscope? They are about 20 to 30 nm across, and a light microscope cannot separate details closer than about 200 nm. You need an electron microscope.