Cell Differentiation (OCR Gateway GCSE Biology: Combined Science)

• Humans are made from trillions of cells, but only of about 250 different cell types
• Specialised cells are cells that have a particular structure and composition of sub-cellular structures
  • The structural differences between different types of cells enables them to perform specific functions
  • This allows organisms to operate more efficiently
• Cells specialise by undergoing a process known as differentiation
  • e.g. to develop into a nerve cell the cytoplasm and cell membrane of an undifferentiated cell must elongate to form connections over large distances
• Most animal cells (except stem cells) differentiate at an early stage during development to become specialised
  • They then lose their ability to differentiate
• The majority of plant cells never lose the ability to differentiate into specialised cell types
  • They retain the ability to fully differentiate throughout the life of a plant

Diagram showing the differentiation of a human cell

Examples of Specialised Cells in Animals Table

Ciliated epithelial cells - the hair-like cilia beat to move mucus and any trapped particles

Nerve cells are long with extensions and branches to allow communication with other nerve cells or organs

Red blood cells are biconcave and contain no nucleus to maximise transport of oxygen

Sperm cells have a tail to enable the sperm to move

An egg cell contains a lot of cytoplasm rich in nutrients

Examples of Specialised Cells in Plants Table

Root hair cell have a large surface area to maximise absorption of water and minerals

Xylem cells lose their top and bottom walls to form a continuous tube through which water moves through

Palisade mesophyll cell contain many chloroplasts to help maximise photosynthesis