Diffusion

• Diffusion:

  • passive transport = no energy involved
  • particals move through bi-layer
  • particals move from high concentration to low concentration along concentration gradient
• examples of substances that utilise simple diffusion:

  • alchohol, steriods, fat soluable substances, oxygen, CO2
• rate of diffusion goes up as concentration gradient increases
• Osmosis:

  • diffusion of water molecules across a selectively permiable membrane
  • passive proccess
• Isotomic solution:

  • equal concentration of ions in solution and cell
• Hypertonic solution:

  • higher concentration of ions in solution then in cell
• Hypotonic solution:

  • lower concentration of ions in solution than in cell
• Osmotic pressure:

  • pressure due to differences in concentration on either side of a differently permiable membrane
• Facilitated transport:

  • same as passive diffusion but uses channel or carrier protines
  • 2 main types: faciltated diffusion, active transport
• Facilitated diffusion:

  • higher concentration to low concentration
  • molecules pass though protine channel (hydrophillic molecules pass through membrane without coming into contact with hydrophobic inner portion)
• Carrier mediated transport:

  • only open on one side of membrane at a time
  • specific substances bind to binding site within protine
  • substances then relesed on other side of membrane
  • specific to particular molecules
• Active transport:

  • active proccess (requires ATP)
  • molecules move against concentration gradient (from low to high)
• Vesticular transport:

  • movement of molecules across mebrane in membranouse sacs called vesticals
  • active proccess
• Endocytosis:

  • liquids/solids move into cell
• Exocytosis:

  • liquids/solids move out of cell
• pinocytosis

  • movement of liquids
• Phagocytosis:

  • movement of solids