Cell Transport

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					CELL TRANSPORT
TEST: TUESDAY 11/09
  CELL MEMBRANE PERMEABILITY

• Semi-
  permeable—
  allows small
  substances to
  pass through
  freely
• Larger
  substances must
  pass through
  channels
• Lipid bilayer
FLUID MOSAIC MODEL
                  DIFFUSION

• Molecules always move from HIGH to
  LOW concentrations
• Occurs due to a concentration
  gradient
• Effective only across a small distance

     Click the pic to
     watch the video


Diffusion/Osmosis Animations
               M & M DEMO

1. Take a petri dish and fill it with water
2. Place 4 different color M&Ms into the
   water
3. Observe what happens

• What is this process called??
             DIFFUSION!!
• Will all the colors evenly distribute in time?
             YES!!
       MEMBRANE TRANSPORT
• Passive transport—
  type of simple
  diffusion
 • Molecules move from
   HIGH to LOW
   concentration
 • Osmosis—diffusion of
   water
 • Facilitated diffusion
   occurs through protein
   channels
    SOLUTE CONCENTRATIONS
• Isotonic: equal amounts of solutes
• Hypotonic: solution has lower solute
  concentration (H20 IN—cell bursts)
• Hypertonic: solution has higher
  concentration of solutes (H20 OUT—cell
  shrinks)




    Diffusion/Osmosis Animations
                     OSMOSIS   Click pic to
                               watch the video

• Diffusion of
  water
• Occurs easily
  through bi-lipid
  layer
• Aquaporins—
  proteins in cell
  membrane,
  allow for
  quicker
  movement of
  water
     FACILITATED DIFFUSION

• Molecules pass through or bind to a
  protein channel to cross a membrane




                               Click above to
                               watch a video
                                   showing
                                 facilitated
                                   diffusion
         CARRIER PROTEINS
• When a substance being transported binds
  to protein
• Moves from HIGH to LOW

				
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