9.3.3 Specialised Cells

• Multicellular


  Made of many cells
• Types of organisms


  • Animals
  • Plants
• Red blood cell


  Function: To carry oxygen around the body and take it to respiring tissues. The oxygen combines to haemoglobin in the RBC
• Red blood cell


  • Packed full of haemoglobin to carry oxygen
  • No nucleus = more space for haemoglobin
  • Large surface area for oxygen to enter in the lungs or leave in respiring tissue
• Sperm cell

  Function: To carry HALF the genetic material for fusion with an egg cell during SEXUAL REPRODUCTION

  
• Sperm cell


  • Large nucleus = carry DNA (genetic material)
  • Long tail (flagellum) for swimming
  • Lots of mitochondria to release energy for swimming
  • Streamlined head for swimming + to enter the egg
  • Acrosome cap. This contains enzymes that help to digest the outside of the egg

  
• Sperm cells are about 0.05mm long!
• After puberty, men make millions of sperm each day!
• Egg cell


  Function: To carry HALF the genetic material for fusion with a sperm cell during SEXUAL REPRODUCTION

  
• Egg cell


  • Nucleus = carry DNA (genetic material)
  • Jelly coat releases chemicals that attract the sperm and prevents too many sperm entering at once (only 1 can fertilise the egg)
  • Large cytoplasm = contains food stores to provide energy once fertilisation has occurred
• Egg cells are about 0.1mm (much larger than sperm)
• After puberty, women release 1 egg each month
• Nerve cell (neurone)


  Function: To carry information as electrical impulses around the body. These electrical impulses are called ACTION POTENTIALS
• Nerve cell (neurone)


  • A long axon to carry action potentials very quickly
  • A myelin sheath wraps around the axon to INSULATE the axon and speed up the movement of action potentials
  • Information can only travel in 1 direction
• White blood cells


  Function: To remove and destroy bacteria, viruses and fungi that could cause illness and disease (part of the immune system)
• White blood cells (phagocytes)


  • Irregular shaped nucleus
  • Ingest (engulf) bacteria and viruses and use enzymes to break them down and destroy them
• In Y10, you will learn about another type of white blood cell: the LYMPHOCYTE

  
• Ciliated cells and goblet cells


  Goblet cells: produce sticky mucus

  Ciliated cells: The hairs can move
• Ciliated and goblet cells


  • Found lining the windpipe down to the lungs (the windpipe is called the trachea)

  Goblet cells = produce sticky mucus to trap substances

  Ciliated cells = waft the mucus, dust and dirt back to the nose and mouth

  Prevents infections in the lungs
• Root hair cells


  Function: To absorb water and mineral ions from the soil
• Root hair cells


  • No chloroplasts = do not get sunlight so can't photosynthesise

  Long projection = Increased surface area for absorption of water and mineral ions

  Lots of mitochondria = to release energy to help take up mineral ions from the soil (they do this in a process called active transport)
• Palisade mesophyll cells


  Function: Site of photosynthesis
• Palisade mesophyll cells


  • The 2nd layer of cells in a leaf

  Packed full of chloroplasts = absorb lots of light for PHOTOSYNTHESIS

  Tall cells = increased surface area = absorb more light