Diffusion

• What is diffusion?

  The net movement of particles (molecules/ions) from an area of higher conc to an area of lower conc
• Which ways will molecules diffuse?

  both ways - but the net movement will be to the area of lower conc

  • this continues until particles are evenly distributed throughout the liquid or gas
• What is the concentration gradient?

  the path from an area of higher concentration to an area of lower concentration
• which way do particles diffuse?

  down a concentration grafient
• what do polar molecules have?

  partial positive and negative charges

  ( non-polar molecules do not)
• what type of process is diffusion?

  passive
• is diffusion an active or passive process?

  passive - no energy is needed for it to happen
• What can particles do?

  Diffuse across cell membranes , as long as they can move freely through the membrane
• what small molecules can diffuse easily through cell membranes?

  oxygen and CO2
• Why can Oxygen and CO2 diffuse easily through cell membranes?

  • small = can pass through spaces between phospholipids
  • non-polar = makes them soluble in lipids = they can dissolve in the hydrophobic bilayer
• what is simple diffusion?


  when molecules diffuse directly through a cell membrane