Cell Recognition (AQA A Level Biology): Revision Note

Cell recognition

• Specific molecules on the surface of cells (and viral particles) enable the body to identify them, allowing it to distinguish between its own cells (‘self’) and foreign cells (‘non-self’)

• These molecules are usually proteins present on the phospholipid bilayer, such as glycoproteins

  • However, glycolipids can also act as similar markers

• These surface proteins enable the body to recognise

  • pathogenic cells

  • abnormal body cells, such as cancerous or pathogen-infected cells

  • toxins (these are chemical rather than cellular, in nature)

  • cells from other individuals from the same species (in order for organ transplants to occur successfully the body must not recognise the cells and tissues of the donated organ as foreign, so that no immune response occurs)

• The surface molecules used by the body to identify cells, viral particles and toxins are known as antigens