Cell differentiation

An unspecialised cell has not yet developed the features needed for a particular job. As it differentiates, its shape and the types or amounts of sub-cellular structures it contains change. The resulting specialised cell has a structure suited to its function.

Almost all cells in a multicellular organism contain the same genetic information. However, different genes are switched on in different cell types. This controls how the cells develop, so cells with the same genetic information can acquire different structures and functions.

For example, when an unspecialised cell develops into a nerve cell, its cell membrane and cytoplasm become elongated. This enables the nerve cell to form connections over long distances. The important link is differentiation → a suitable structure → a particular function.

Differentiation in animals

Most types of animal cell differentiate at an early stage of development. As the young animal develops, its cells become specialised to form its different tissues and organs. Most specialised animal cells then lose the ability to differentiate into other cell types.

Some unspecialised cells remain in adult animals and can still differentiate. These provide a source of new specialised cells when tissues need them.

In a mature animal, cell division is mainly restricted to repair and replacement rather than growth. For example, new cells replace worn-out skin cells and help repair damaged tissue after a wound. Division supplies new cells; differentiation allows suitable unspecialised cells to develop the features needed for their role in the tissue.

Differentiation throughout a plant’s life

Many types of plant cell retain the ability to differentiate throughout the plant’s life. This contrasts with the early differentiation of most animal cell types.

Plants therefore continue to produce new specialised cells as they grow and develop. The distinction is not that every plant cell can become any other cell type: it is that many plant cells retain the ability to differentiate, whereas most animal cell types differentiate early.

• Differentiation produces specialised cells with structures suited to particular functions.
• It enables a developing multicellular organism to form different cell types for different jobs.
• Differentiating cells change shape and acquire different sub-cellular structures.
• Division: more cells. Differentiation: specialised cells.

Animals and plants

• Animals: most cell types differentiate early in development.
• Mature animals: cell division is mainly for repair and replacement.
• Plants: many cell types retain the ability to differentiate throughout life.