TEST: FRIDAY 11/11CELL TRANSPORT

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

Diffusion/Osmosis Animations

Click the pic to watch the video

M & M DEMO

1. Take a petri dish and fill it with water2. Place 4 different color M&Ms into the

water3. 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

•Diffusion of water•Occurs easily through bi-lipid layer

Click pic to watch the video

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

FACILITATE DIFFUSION THROUGH CARRIER PROTEINS

• When a substance being transported binds to protein• Moves from HIGH to LOW

Click above to watch a video

showing facilitated diffusion