Cell biology

• Animal cells are eukaryotic cells
• DNA

  Forms chromosomes contained in the nucleus
• Nucleus

  Contains DNA
• Mitochondria


  Energy is released through respiration
• Ribosomes


  Site of protein synthesis
• Cytoplasm


  Where chemical reactions happen
• Cell wall

  Membrane controls the movement of substances
• Plant Cell


  Plant cells are eukaryotic cells
• Bacteria

  Prokaryotic cell, no nucleus, smaller
• Bacteria


  • Cell wall strengthens the cell
  • Cell membrane controls movement
  • Plasmid DNA rings
  • Cytoplasm chemical reactions
• DNA

  Bacterial DNA is in rings (plasmids)
• Microscopes

  Magnification = Image Size / Actual Size
• Light Microscopes

  • Light forms images
  • Can use living samples
  • Relatively cheap
• Electron Microscopes


  • Beams of electrons form images
  • High magnification
  • High resolution
  • Can't use living samples
  • Expensive
• Sperm Cell

  Function: to fertilise an egg, lots of mitochondria for respiration, tail to swim
• Red Blood Cell

  Function: to transport oxygen around the body, no nucleus to increase space, haemoglobin binds oxygen, bi-concave shape
• Muscle Cell

  Function: to contract and relax, contains protein fibres, mitochondria for respiration
• Nerve Cell

  Function: to carry electrical impulses, branched endings (dendrites) to make connections, myelin sheath insulates axon to increase transmission speed
• Root Hair Cell

  Function: to absorb mineral ions and water, large surface area, lots of mitochondria
• Diffusion

  The spreading out of particles where particles move from an area of higher concentration to a lower concentration, down the concentration gradient, no energy required (passive process)
• Diffusion

  • Nutrients in blood to capillaries
  • Oxygen in air to alveoli
  • Oxygen in water to fish gills
  • Carbon dioxide in blood to water
  • Carbon dioxide in air to leaves
  • Oxygen in leaves to air
• Osmosis

  The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane, water moves from an area of lower concentration to higher concentration, no energy required (passive process)
• Osmosis

  • Nutrients in soil to root hair cells
• Active Transport

  The movement of particles from dilute to concentrated areas using energy, particles move against the concentration gradient, uses energy released by respiration
• Active Transport

  • Sugar molecules from small intestine to blood
  • Mineral ions from soil to roots
• carbon dioxide + water → glucose + oxygen