Passive Cell Transport

Concentration Gradient The difference in concentrations on the two different sides of a membrane. HIGH CONCENTRATION Concentration: the amount of a substance in a particular area WHICH WAY WOULD THE COWS LIKE TO GO? LOW CONCENTRATION

Particles naturally move down the concentration gradient ! High Concentration Low Concentration

Passive Transport When the cell does NOT use energy to move particles Particles move randomly (Brownian motion) Particles move from HIGH to LOW concentrations Move down the concentration gradient

Passive Transport Requires NO ENERGY Moves from HIGH to LOW Concentrations

3 Types of Passive Transport Diffusion Osmosis Facilitated Diffusion

1. Diffusion Movement of particles from HIGH concentration to LOW concentration Diffusion continues until all molecules are evenly spaced (equilibrium is reached)

Diffusion of Liquids

Diffusion from high to low concentration

Factors affecting the rate of diffusion Concentration gradient Temperature Pressure Increase any of the three above factors and the rate of diffusion increases.

2. Osmosis Osmosis is the diffusion of WATER across a selectively permeable membrane The water will move across a membrane to balance concentrations

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Remember: Salt SUCKS!

3. Facilitated Diffusion Diffusion of particles (High to Low concentration) that uses transport proteins (channel proteins or carrier proteins)