AQA Biology 4.1.1.3–4.1.1.4

Cell specialisation and differentiation

A cell’s structure fits its job. Give a cell a job, choose the features it would need, then compare with the real thing.

Combined Science · Higher tier

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A kitchen drawer.

A whisk, a sieve and a sponge. Each is shaped for one job, and none of them would be much good at the others’.

If you had to guess, would a cell that has to swim look the same as a cell that has to soak up water?

Differentiation

A cell becomes specialised as it differentiates.

As a cell differentiates, it gains different sub-cellular structures that let it carry out a certain job. Then it is a specialised cell. Tap animals or plants.

Cells that can still become many types are stem cells: in Stem cells.

Design the cell

Give it a job. What would it need?

Pick a job, choose every feature you think the cell would need, then compare with the real cell.

The job

Swim to an egg and fertilise it.

Think again · root hair cells

“Root hair cells take in water by active transport.”

Your call

Choose

How do water and mineral ions get into a root hair cell?

Sort

Which cell has it?

Place each feature with its cell.

Tap a card, then tap the box it belongs in. Tap a placed card to take it back.

Command words in this lesson

Describe: The feature: what it looks like.
Explain how: Feature, then how it helps the job: “so that…”.
Suggest: For a cell you’re given: use its job.

Key fact

As a cell differentiates it gains the sub-cellular structures it needs for its job. Most animal cells differentiate early; many plant cells can differentiate throughout life.

Key note · AQA 4.1.1.3–4.1.1.4

Cell specialisation and differentiation

As a cell differentiates it gains different sub-cellular structures, so it can carry out a certain job: it becomes specialised.
Most animal cells differentiate early; in mature animals, division is mainly for repair and replacement. Many plant cells can differentiate throughout life.
Sperm: tail, many mitochondria, enzymes, half the chromosomes. Nerve: long axon, branched endings. Muscle: protein fibres that contract, many mitochondria.
Root hair: large surface area; many mitochondria for active transport of mineral ions. Xylem: dead, hollow, lignin. Phloem: elongated living cells, pores in the end walls.

Photograph this card. Tomorrow, cover it and say each line first.

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Not sure how to link a feature to a job?

Cell drawings are schematic and not to scale.