Cell Differentiation (AQA GCSE Biology): Revision Note

Differentiation: Basics

• Structural differences between cell types enable them to perform specific functions within the organism

• Cell differentiation is an important process by which a cell changes to become specialised

  • Differentiation is what allows a single fertilised egg to produce the many cell types a multicellular organism needs so that different cells can carry out different jobs

  • Cells that have not differentiated are therefore unspecialised

• Almost all of the cells in a multicellular organism will contain the same genetic information (the same genes or alleles).

• Only some of those genes are switched on in any one cell, and this controls how the cell develops.

• When a cell differentiates, it develops a structure and composition of sub-cellular structures which enables it to carry out a certain function

  • For example, to form a nerve cell the cytoplasm and cell membrane of an undifferentiated cell must elongate to form connections over large distances

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Differentiation & development

• As a multicellular organism develops, its cells differentiate to form specialised cells

• In an animal, most cells differentiate at an early stage of its development.

• Cell division is mainly restricted to repair and replacement in mature animals

  • Animal cells lose their ability to differentiate after they have become specialised early in the life of the animal

  • Some cells retain the ability to differentiate throughout an animal's life. These cells are called adult stem cells

  • They mainly replace cells for tissue repair (such as blood or skin cells)

• Plants have stem cells that keep the ability to differentiate throughout the plant's life, located in the meristem