Cell differentiation

• Embryo

  • Cell differentiation is happens during an organisms development.
  • Organisms start as one cell.
  • These cells divide to form embryos that differentiate (specialise) to produce cells that can perform all the bodys functions.
• Adult animals

  • Cell differentiation is rare in mature (adult) animals.
  • Their cells mostly divide (one cell splits to create 2 cells) in order to replace cells and repair tissues.
  • New tissues are rarely created.
• Sperm cells


  Middle section:

  • Is filled with mitochondria so the sperm cel has the energy it needs to travel a long distance to reach the egg cell.

  Flagellum:

  • (Tail) is used for the cells motion. This allows sperm to travel towards the egg cell.

  Head:

  • Contains the sperms nucleus, carries one half of an organisms genetic material.
  • This combines the egg cells half of genetic material to fertilise the egg cell. - Acrosome, it is found at the tip of the head. It contains the digestive enzymes needed to penetrate (break into) an egg cell.
• How do sperm cells move towards their target?

  Sperm cells spin their tails in a corkscrew motion
• What is the purpose of the corkscrew motion of sperm cells?


  To move themselves towards their target, the egg
• What is created when the sperm fuses with the egg?

  A complete genome is formed, containing all the DNA needed to make a whole organism.
• Nerve Cells

  Axon - Part of the cell that electrical signals travel along

  Myelin sheath - A sheath made up of a material called myelin surrounds the axon of the nerve cel. This stops electrical nerve signals leaking out of the nerve cell. This increases the speed of transmission (travel) of electrical signals.

  Dendrites - Branches of a nerve cel. Several dendrites spread outwards from the cell body to transfer electrical messages to other neurons. Electrical messages travel between neurons at synapses.
• Muscle cells

  Mitochondria - A muscle cell contains lots of mitochondria to generate lots of energy for motion.

  Protein fibres - Within the cell can contract, allowing the muscle to move.
• Root hair cells

  No chloroplasts - These cells are located underground. This means that they do not contains chloroplasts (there is no light for photosynthesis). Long projections- Root hair cells have long projections that increase the surface area that the plant can use to absorb water and minerals.