Specialised cells

• Red blood cells - adaptations

  • Contain large amounts of haemoglobin molecules which enable the red blood cells to transport oxygen around the body.
  • Small diameter and no nucleus so there is more space for haemoglobin molecules so larger amounts of oxygen can be transported.
  • Disc, biconcave shape to increase the surface area:volume to increase the rate of oxygen diffusing in and out of the cell.
  • Elastic membrane which enables the red blood cells to squeeze through narrow blood capillaries.
  • If they don't work properly you can get anaemia.
• Muscle cell - function

  • Stores glycogen which is broken down into glucose and used in cellular respiration.
  • Contract to squeeze food through the gut.
• Root hair cell - adaptations

  • Contains a cellular protrusion known as the root hair which increases the surface area:volume to increase the rate of water and mineral salts being absorbed.
  • Contains large numbers of mitochondria to allow the release of energy during aerobic respiration to absorb mineral salts from the soil by active transport.
  • Large permanent vacuole that speeds up the movement of water.
  • No chloroplasts.
  • Thin cell wall to allow water to pass through easily.
• Muscle cell - adaptations

  • Can contract and relax
  • contain large amounts of mitochondria which allows muscle cells to release energy during aerobic respiration for muscle contraction.
  • If they don't work properly you can have impaired mobility.
• Sperm cell - function

  • To carry DNA for reproduction.
  • To fertilise the egg.
• Sperm cell - adaptations

  • Large nucleus which contains genetic information to make a baby.
  • Lots of mitochondria to release energy needed to move.
  • Tail to swim to egg.
  • Acrosome that contains enzymes to digest and penetrate the outer layer of the egg.
  • If they don't work properly you can have infertility.
• Nerve cell - function

  • Carries electrical impulses around the body.
  • If they don't work properly: paralysis, death.
• Nerve cell - adaptations

  • Long and thin
  • Forms connections with other neurones.
  • Can carry electrical impulses in one direction.
  • Have an insulating layer of fat called the myelin sheath to prevent the impulses from being lost.
• Root hair cell - function

  • Absorbs minerals and water from soil.
  • Found in plants (roots) and are needed to absorb water.
• Xylem cell - function

  • Allows transport of water and mineral ions from the roots of a plant to the highest leaves and shoots.
• Xylem cell - adaptations

  • Contains a special chemical called lignin which strengthens and supports the plant. It helps the vessel to withstand the pressure of water moving up the plant.
  • They lose their end walls so the xylem forms a continuous, hollow tube.
• Phloem tubes - function

  Transport of substances is known as translocation.

  The phloem moves food substances that the plant has produced by photosynthesis to where they are needed for processes such as:

  • growing parts of the plant for immediate use
  • storage organs such as bulbs and tubers
  • developing seeds
• Phloem tubes - adaptations

  • Made from living plant cells because the cells don't become lignified.
  • Transport products of photosynthesis (includes sucrose and amino acids dissolved in water) up and down the plant.
  • Contain sieve plates which allow the movement of food.