What Do All Cells Share?
Both animal and plant cells are eukaryotic — they have a clear nucleus enclosed by a membrane. They share these key structures:
| Structure | Function |
|---|---|
| Cell membrane | Controls what enters and leaves the cell |
| Nucleus | Contains DNA; controls cell activities |
| Cytoplasm | Fluid filling the cell; site of chemical reactions |
| Mitochondria | Produce energy through respiration |
| Ribosomes | Build proteins (too small to see under a normal microscope) |
What Only Plant Cells Have
Plant cells have three additional structures that animal cells lack:
1. Cell wall
- Made of cellulose, a tough, rigid material
- Found outside the cell membrane
- Gives the cell a fixed, box-like shape
- Provides support and prevents over-expansion
2. Chloroplasts
- Contain the green pigment chlorophyll
- Absorb light energy for photosynthesis
- Found in cells that are exposed to light (mainly leaf cells)
- Not found in root cells (no light underground)
3. Large central vacuole
- Filled with cell sap (water and dissolved substances)
- Can take up 90% of the cell's volume in a mature plant
- Maintains cell pressure (turgor) — makes the plant firm
- Storage for nutrients and waste products
When a plant does not get enough water, its vacuoles shrink and the cells lose their rigidity — the plant wilts. If you water it in time, the vacuoles refill and the plant stands upright again. This is turgor pressure in action.
Why Do the Differences Exist?
The extra plant cell structures reflect the different needs of plants:
- Cell wall — plants need structural support (they can't move; the cell wall acts as a skeleton)
- Chloroplasts — plants make their own food using sunlight (animals get energy by eating)
- Vacuole — plants can't drink, so they store water; they also accumulate waste products the cell wall stops from passing out
A quick memory trick: "Plants like C.V.W." — Chloroplasts, Vacuole (large), Wall (cell). These are the 3 extras that only plant cells have.
Real world: Microscopy in school labs
A classic school experiment is to prepare slides of both onion cells (plant cells) and cheek cells (animal cells) and compare them under a light microscope. You can clearly see the rectangular, box-shaped plant cells with their visible cell walls, compared to the irregular, rounded animal cells. Both show a nucleus, but only the plant cells have a visible cell wall.
Real world: Wilting plants and food freshness
When salad leaves wilt in the fridge, it is because the large central vacuoles in plant cells have lost water. Animal cells never wilt like this because they have no large vacuole — their shape is maintained by other means. Understanding this difference helps explain why plant-based foods are stored differently from animal-based foods.
Real world: Vegetarian and vegan diets
Plant cells and animal cells provide different nutrients. Plant cells provide dietary fibre (from cell walls), vitamins, and carbohydrates, while animal cells provide complete proteins and vitamin B12. Knowing the structural differences between plant and animal cells helps explain why nutritionists recommend eating a variety of both to get all essential nutrients.
Where do you see this in real life? The difference between plant and animal cells is visible in everyday life: the crunch of a fresh carrot (plant cells with rigid walls and turgid vacuoles) versus the soft texture of meat (animal cells with no wall). These different textures are a direct result of cell structure.