2.2.3Structure & Functions in Living Organisms
Importance of Cell Differentiation — Edexcel International GCSE Biology 4BI1 Revision Notes & Topical Questions
5 min read 4 parts Lesson 12 of 21 Unit quiz
Part 1 of 4What Differentiation Is
A fertilised egg divides to form many cells, which then take on different structures and jobs.
Differentiation
- The process by which an unspecialised cell changes its structure and contents so that it can carry out one particular function.
Gene control
- Which genes in the nucleus are switched on decides what proteins a cell makes, and so what type of specialised cell it becomes.
Stem cells
- Undifferentiated cells that divide by mitosis and can produce either more stem cells or cells that go on to differentiate.
Why it matters
- Specialised cells working together in tissues and organs let a multicellular organism carry out many functions efficiently.
Part 2 of 4Differentiation in Animals and Plants
Differentiation in Animals and Plants
Animals
- Most animal cells differentiate early in development and then lose the ability to become other cell types.
Adult stem cells
- Some tissues, such as bone marrow, keep stem cells throughout life to replace and repair cells like blood and skin.
Plants
- Many plant cells keep the ability to differentiate throughout the whole life of the plant, not only during early growth.
Consequence
- This lets a small piece of plant tissue grow into a complete new plant, which animal tissue pieces cannot do.
Part 3 of 4Examples of Specialised Cells
In each case the shape and contents of the cell suit its job.
Ciliated cell
- Hair-like cilia on the surface beat to move mucus and trapped particles up the trachea and bronchi towards the throat.
Nerve cell
- A long, thin cell that carries electrical impulses over large distances, with a fatty sheath that insulates the axon.
Red blood cell
- A biconcave disc without a nucleus, packed with haemoglobin, giving a large surface area and room to carry oxygen.
Root hair cell
- A long extension increases surface area for absorbing water and mineral ions from the soil, and the wall is thin.
Palisade cell
- A tall, tightly packed cell near the top of the leaf containing many chloroplasts to absorb light for photosynthesis.
| Cell | Key adaptation | Function |
|---|---|---|
| Red blood cell | No nucleus, haemoglobin | Transport oxygen |
| Root hair cell | Long extension | Absorb water and ions |
| Palisade cell | Many chloroplasts | Photosynthesis |
Part 4 of 4Exam Checklist & Tips
2.2.3 – Key Points for the Exam
- Differentiation The process by which an unspecialised cell becomes specialised for a particular function.
- Specialised cell A cell with a structure that is adapted to carry out a specific function.
- Stem cell An undifferentiated cell able to divide by mitosis and form other cell types.
- Tissue A group of similar cells that work together to perform a function.
- Haemoglobin The red protein in red blood cells that binds and carries oxygen.
Common Mistakes
- Describing differentiation as cells dividing; it is the change in structure that gives a cell a specific job.
- Stating that specialised cells contain different genes; they contain the same genes but use different ones.
- Saying red blood cells have a nucleus;
- mature mammalian red blood cells do not, which makes room for haemoglobin.
- Forgetting to link the structure of a cell to its function in an answer.
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Cambridge 9700 AS Biology
Core Formula
Magnification Triangle & Unit Conversion
Formula: M = I / A ⇔ A = I / M ⇔ I = M × A
Units: 1 mm = 1,000 μm = 1,000,000 nm.
Rule: Convert Image size (ruler mm) to μm by ×1,000 before dividing by Actual size.