Cell Structure and Function · Grade 10
What is the difference between a plant cell, an animal cell and a bacterium?
A plant cell has three things an animal cell does not: a rigid cell wall, chloroplasts, and a large central vacuole. A bacterium differs from both far more deeply — it has no nucleus and no membrane-bound organelles, and its genetic material floats within the cell. None of these differences is arbitrary; each serves a way of living.
Learning objectives
- List what a plant cell has that an animal cell lacks and explain what each addition is for
- Distinguish a prokaryotic cell from a eukaryotic cell by three concrete features
- Explain how a rigid cell wall and a large vacuole together hold a plant upright
- Explain why a bacterium can divide within twenty minutes and a human cell cannot
What a plant has and we do not
A cell wall made of cellulose surrounds the membrane on the outside and gives the cell a fixed shape. It is also what lets the cell fill with water without bursting.
Chloroplasts carry out photosynthesis. An animal cell does not make its own food, so it has none.
A large central vacuole fills most of a plant cell's volume and holds water and dissolved substances. When it is full it presses outwards on the wall and the cell becomes firm — together, wall and vacuole are what hold a plant upright without a skeleton.
Prokaryote and eukaryote
The deep division is not between plant and animal but between a bacterium and both of them. A bacterium has no nucleus: its genetic material sits in a region of the cell with no membrane around it.
Nor does it have membrane-bound organelles — no mitochondrion, no endoplasmic reticulum. It is also far smaller, a few micrometres against tens.
It does have ribosomes, because every cell must build proteins. A ribosome is not membrane-bound either — which is exactly why it is found in both.
Why a bacterium divides so fast
A bacterium can divide in about twenty minutes in good conditions. The reason is that it has far less to copy and organise: a single circular chromosome, no nuclear membrane to dismantle and rebuild, and no elaborate division machinery.
A human cell copies a far larger quantity of genetic material, breaks down and rebuilds the nuclear envelope, and shares out the organelles between the two daughter cells. That takes hours — and it is also far more accurate.
Worked examples
An image shows a rigid wall and chloroplasts. What is it?
- A cell wall is present in plants and not in animals
- Chloroplasts carry out photosynthesis
- A bacterium has no membrane-bound organelles
Answer: A plant cell
Give three real differences between a prokaryote and a eukaryote
- Nucleus: present in the eukaryote, absent in the prokaryote
- Membrane-bound organelles: only in the eukaryote
- Size: a prokaryote is smaller by an order of magnitude
Answer: Nucleus, membrane-bound organelles, and size
An unwatered plant wilts. What has happened at cell level?
- The vacuole has lost water
- It has stopped pressing on the wall
- The cell has lost its firmness
Answer: Without pressure from the vacuole nothing holds the plant upright
Common mistakes
- Saying a plant cell has no membrane
- It has both a membrane and a wall. The wall sits outside the membrane and does not replace it — it is not selective at all.
- Thinking a bacterium has no genetic material
- It has, but with no membrane around it. The difference is in the organisation, not in the existence.
- Treating a bacterium as a small plant cell
- The prokaryote–eukaryote divide is deeper than the plant–animal one. Both of the latter have a nucleus and organelles; a bacterium has neither.
What to remember
- Plant: wall, chloroplasts, large vacuole.
- Bacterium: no nucleus, no membrane-bound organelles.
- Ribosomes are in all of them.
- Wall and vacuole together hold a plant up.
More in Cell Structure and Function
- What can a microscope show you, and what can it not?
- How is the cell membrane built and what does it decide?
- What is the difference between diffusion, osmosis and active transport?
- What are the organelles and how do you infer function from structure?
- How does a protein travel from the gene to outside the cell?