BIOLOGY- specialised cells

• Specialised cells


  Different types of cells that make up complex organisms like animals and plants
• Examples of specialised cells in animals

  • Sperm cells
  • Muscle cells
  • Nerve cells
• Examples of specialised cells in plants

  • Root hair cells
  • Phloem cells
  • Xylem cells
• Sperm cell


  • Has half the genetic material of a normal adult cell
  • Has a flagellum (long tail) to swim to ovum
  • Is streamlined to swim to ovum
  • Has many mitochondria to provide energy for swimming
  • Has digestive enzymes to break into egg (digest outer layer of ovum)
• Differentiation


  The process by which cells become specialized
• Differentiationprocess


  1. Single zygote cell divides

  2. Cells remain identical at first

  3. Cells then undergo changes to become specialised
• Nerve cells

  • Long axon to transmit electrical impulses and to cover more distance
  • Axon covered in myelin to insulate and speed up transmission
  • Dendrites to increase surface area for connections
  • Synapses at the end of the axon to allow the impulse to pass from one nerve cell to another
• Muscle cells


  • Contain protein fibers that can contract to shorten the cell
  • Packed with mitochondria to provide energy for contraction
• Differentiation


  The process where cells become specialized
• Root hair cells


  • Increase the surface area of the root to absorb water and dissolved minerals more effectively
  • Do not contain chloroplasts
• Xylem cells


  • Have very thick walls containing lignin to provide support
  • Have no internal structures like nucleus, cytoplasm, vacuole or chloroplasts to allow easy flow of water and dissolved minerals
  • Xylem cells form long tubes which carry water and dissolved minerals from the roots to the leaves