AQA GCSE Differentiation of Cells(Biology)
Differentiation of Cells
Undifferentiated cells are known as stem cells.
Stem cells can undergo a process called differentiation in order to become specialised cells.
Importance of Differentiation.
Differentiation is important because:
Specialisation of function – Differentiation allows cells to become specialised, such as nerve cells for transmitting impulses, muscle cells for contraction, or red blood cells for carrying oxygen. Without differentiation, all cells would be the same and organisms couldn’t perform complex tasks.
Efficient organisation – Specialised cells can work together to form tissues, organs and organ systems, each carrying out specific roles that keep the organism alive. For example, muscle tissue contracts to enable movement, while xylem tissue in plants transports water.
Multicellular survival – Differentiation is essential for multicellular organisms because a single type of cell cannot perform all the functions needed to survive. It ensures that life processes like respiration, transport, communication, and reproduction are carried out effectively.
Growth and development – In early stages of life (e.g. embryo development), differentiation is crucial for forming the wide variety of cells that make up the body’s systems.
Differentiation in animal cells.
As an organism develops, cells differentiate to form different types of cells, these are known as specialised cells.
Most animal cells lose the ability to differentiate at an early stage of development (e.g. in the embryo).
After this stage, animal cells are usually specialised and can only divide to produce the same type of cell.
This is why repairing damage in animals is more limited.
An embryo is a ball of cells as shown below.
The zygote (fertilised egg cell) that is formed as a result of fertilisation will undergo mitosis to form a 2 cell embryo, which cells can divide to form a 4 cell embryo. These embryonic cells can undergo differentiation to form specialised cell types.
However, once differentiated, into specialised cell types, reversing this process is difficult and so is further differentiation in animal cells.
Differentiation in Plant cells
Many plant cells, especially those in the meristems (growing regions at root and shoot tips), retain the ability to differentiate throughout life.
This means plants can keep producing new specialised cells, which is why we can take cuttings and grow whole new plants.
How differentiation changes cells.
As a cell differentiates, it doesn’t just change shape — it also develops different sub-cellular structures (like mitochondria, ribosomes, vacuoles, etc.) that equip it for its specialised role.
Examples:
A sperm cell develops many mitochondria to release energy for swimming, and a tail for movement.
A root hair cell develops a long extension (root hair) to increase surface area for water/mineral absorption.
A muscle cell develops protein filaments and many mitochondria to release energy for muscle contraction.
A phloem sieve cell loses much of its internal structure to allow transport of sugars through the plant.
Cell Division in Mature Animals
In early development (embryo/young animals), cell division is used for growth and differentiation, producing all the different specialised cells needed.
In mature animals, most cells are already differentiated and specialised.
This means cell division is mainly restricted to replacement of worn-out or damaged cells, rather than creating new types of cells.
Skin cells divide to replace those lost at the surface.
Blood cells are continuously produced from stem cells in bone marrow to replace old ones.
Liver cells can divide to repair damage after injury.
But highly specialised cells like nerve cells in the brain and spinal cord usually cannot divide once mature.
Practice Question
1.Define the term cell differentiation.
2.Explain why cell differentiation is important in multicellular organisms.
3.Describe one difference between cell differentiation in plants and animals.
4.Give one example of a specialised animal cell. Describe one of its adaptations and explain how that helps it carry out its function.
5.A sperm cell contains many mitochondria. Explain why.
6.Compare the roles of xylem cells and phloem cells in plants, and explain how their structures are adapted for these roles.
7.Why can cuttings from plants be used to grow whole new plants, but this is not possible in most animals?
8.In mature animals, what is the main purpose of cell division? Give two examples of tissues where this happens.
9.Discuss how cell differentiation allows organisms to grow and survive. In your answer, you should refer to both plants and animals.