specialised cells

• Animal cells may be specialised to carry out a particular function
• Cilia are tiny hair like structures on the surface of some cells . They can move in organised ways to push substances past the surface of the cell . Cilia cells line the trachea or windpipe to sweep away the mucus away from the lungs carrying away dirt and bacteria
• As and organism develops cells differentiate to form different specialised cells

  • most types of animal cells differentiate at an early stage
  • cells acquire different structures so they can carry out a particular function
• Sperm cells carry the male genes to the female egg. A sperm cell has a tail that helps it swim to the egg. Many mitochondria to release energy needed for the tail to move. Enzymes in its acrosome to digest the outer layers of an egg.
• Nerve cells carry electrical impulses from one part of the body to another which may very far apart .

  A typical nerve cell has:

  • a long axon to connect distant parts
  • tiny finger like dendrites that make connections with other nerve cells
• Root hair cells are found on the surface of plant roots . They absorb water and mineral ions from the soil they have:

  • a large vacuole to increase the rate of osmosis
  • many mitochondria to release energy needed for the active transport of mineral ions
• Xylem cells form the transport tissue that carries water and minerals from the roots to the rest of the plant.

  They have:

  • Lignin it builds up in the xylem and these die to form hollow tubes to support and strengthen
  • no end walls so water and mineral ions can flow easily through the plant
  • pits that let water and ions move out