Facilitated Diffusion

• What does facilitated diffusion use?


  carrier proteins and protein channels
• What would some larger molecules do because they are so big?


  diffuse extremely slowly through the phospholipid bilayer because they are so big
• give 2 examples of larger molecules?


  amino acids

  glucose
• give 2 examples of charged particles?


  • ions
  • polar molecules
• what is a polar molecule?


  molecules with an uneven distribution of charge
• why would charged particles diffuse slowly?


  Because they are water soluble, and the centre of the bilayer is hydrophobic
• Which molecules would diffuse slowly?


  large molecules

  charged PARTICLES
• How do large or charged particles diffuse quicker?


  They diffuse through carrier proteins or channel proteins in the membrane instead- this is called FACILITATED DIFFUSION
• give details about facilitated diffusion and concentration gradients?


  Facilitated diffusion moves particles down a concentration gradient, from a higher to lower concentration
• does facilitated diffusion use energy?


  no
• why is facilitated diffusion a passive process?


  it doesn't use energy
• is facilitated diffusion an active or passive process and WHY?


  PASSIVE because it doesn't use energy
• What do carrier proteins do?


  Move large molecules across membranes, down their concentration gradient
• what do different carrier proteins do?


  Facilitate the diffusion of different molecules
• how do carrier proteins facilitate the diffusion of large molecules?


  1. first a large molecule attaches to a carrier protein in the membrane
  2. then the protein CHANGES SHAPE
  3. this releases the molecule on the opposite side of the membrane
• What do carrier proteins move?


  LARGE MOLECULES
• What do channel proteins facilitate the diffusion of?


  CHARGED PARTICLES
• What do channel proteins do?


  Channel proteins form pores in the membrane for charged particles to diffuse through (down their concentration gradient)
• what do different channel proteins do?


  facilitate the diffusion of different charged particles