Differentiation + specialisation

• Differentiation is the process by which a cell becomes specialised for its job.
• In most animal cells the ability to differentiate is lost at an early age, after they have become specialised. Plant cells don't ever lose this ability.
• Example of specialised cell:

  Sperm cells are specialised for reproduction

  • long tail
  • lot of mitochondria
  • enzymes in head to digest through egg cell membrane
• Example of specialised cell:

  Nerve cells are specialised for rapid signalling

  • long (to cover more distance)
  • branched connections at ends to connect to other nerve cells and form network
  • carry electrical signals
• Example of specialised cell:

  Muscle cells are specialised for contraction

  • long (so have space to contract)
  • contain lots of mitochondria to generate energy needed for contraction
• Example of specialised cell:

  Root hair cells are specialised for absorbing water and minerals

  • on surface of plant roots
  • gives plant a big surface area for absorbing the above from soil
• Example of specialised cell:

  Phloem and xylem are specialised for transporting substances

  • phloem and xylem cells form phloem and xylem tubes
  • tubes transport substances such as food and water around plants
  • cells are long and joined end to end
  • xylem cells are hollow
  • phloem cells have very few subcellular structures so stuff can flow through them