diffusion

• the net movement of particles from a higher concentration to a lower concentration.
• diffusion is a passive process
• the steeper the concentration gradient the faster the rate of diffusion
• the thinner the exchange surface the faster the rate of diffusion
• the larger the surface area the faster the rate of diffusion
• facilitated diffusion takes place with charged molecules
• facilitated diffusion diffuse through carrier and channel proteins
• carrier proteins work by:

  • the large molecule attaches to a carrier protein
  • the protein changes shape
  • this releases the molecule on the opposite side of the membrane
• channel proteins form pores in the membrane and allows charged particles to pass through
• the higher the concentration gradient the faster the rate of faciliation of diffusion
• once the channel and carrier proteins are being used the rate of facilitated diffusion can no longer increase