cell specialisation

• • most animal cells are specialised
  • they have adaptations which help them to carry out their particular function
  • when cells become specialised it is called differentiation
• whats the job of a nerve cell?

  to send electrical impulses around the body
• what is the axon in the nerve cell?

  the axon carries the electrical impulses from one part of the body to another
• what is the myelin in a nerve cell?

  it insulates the axon and speeds up the transmission of nerve impulses
• what are synapses on a nerve cell?

  synapses are junctions which allow the impulse to pass from one nerve cell to another
• what are the dendrites in a nerve cell?

  dendrites increase the surface area so that other nerve cells can connect more easily
• muscle cells can contract

  (get shorter)
• muscle cells contain protein fibres which can change their length
• what happens when a muscle cell contracts?

  the protein fibres shorten decreasing the length of the cell
• what do muscle cells include?

  they are packed full of mitochondria to provide energy for muscle contraction
• what do muscle cells form?

  they work together to form muscle tissue
• how are root hair cells adapted to its function?

  they have hairs and these hairs increase the surface area of the root so it can absorb water and dissolved minerals more effectively
• the root hair cell increases the surface area of the root
• root hair cells don't contain chloroplasts because they are underground
• where are xylems found?

  in the plant stem, they form long tubes
• what does the xylem carry?

  water and dissolved minerals from the roots to the leaves
• how are xylem cells adapted for its function?

  they have very thick walls containing lignin this provides support to the plant however because they are sealed with lignin it causes the xylem to die
• what is another way that xylem is adapted to its function?

  the end walls between the cells have broken down this means that the cells now form a long tube so water and dissolved minerals can flow easily
• xylem cells have got no nucleus, cytoplasm, vacuole or chloroplasts this makes it easier for water and minerals to flow
• what are phloem tubes?

  the carry dissolved sugars up and down the plant
• what is a phloem vessel cell?

  they have no nucleus and only limited cytoplasm this allows for the dissolved sugars to move through the cell interior
• what are sieve plates on the phloem tube?

  the end walls of the vessel cells have pores called sieve plates which allow dissolved sugars to move through the cell interior
• each phloem vessel cell has a companion cell connected by pores. the mitochondria in the companion cells provides energy in the phloem vessel cells