Diffusion & OsmosisDiffusion & Osmosis

DiffusionDiffusion

The movement of molecules The movement of molecules from an area in which from an area in which they are highly they are highly concentrated to an area concentrated to an area in which they are less in which they are less concentrated.concentrated.

DiffusionDiffusion

OsmosisOsmosis

The diffusion of The diffusion of waterwater across a across a selectively permeable selectively permeable membranemembrane..

Osmosis is a type of Passive Osmosis is a type of Passive Transport.Transport.

Osmosis requires Osmosis requires NO ENERGYNO ENERGY..

OsmosisOsmosis HypertonicHypertonic- a - a solution that causes solution that causes a cell to shrink a cell to shrink because of Osmosis.because of Osmosis.

HypotonicHypotonic- a - a solution that causes solution that causes a cell to swell a cell to swell because of Osmosis.because of Osmosis.

IsotonicIsotonic- a solution - a solution that causes no that causes no change in the size change in the size of the cellof the cell

OsmosisOsmosis In this picture a red In this picture a red blood cell is put in blood cell is put in a glass of distilled a glass of distilled water. Because there water. Because there is a higher is a higher concentration of concentration of water outside the water outside the cell, water enters cell, water enters the cell by the cell by OSMOSISOSMOSIS.  .  In this case too much In this case too much water enters and the water enters and the cell swells to the cell swells to the point of bursting point of bursting open.  open. 

Selectively Permeable Selectively Permeable

A membrane that allows only A membrane that allows only certain materials to cross it certain materials to cross it

Materials pass through Materials pass through porespores in in the membranethe membrane

SummarySummary Diffusion is the movement of molecules Diffusion is the movement of molecules from an area of higher concentration from an area of higher concentration to an area of lesser concentration.to an area of lesser concentration.

Osmosis is the movement of Osmosis is the movement of water thru water thru a semi permeable membrane.a semi permeable membrane.

Active transport requires energyActive transport requires energy. . (molecules move from an area of lesser (molecules move from an area of lesser to higher concentration)to higher concentration)

Passive transport needs Passive transport needs NO ENERGYNO ENERGY! ! (molecules move from an area of higher (molecules move from an area of higher to lesser concentration).to lesser concentration).

Why are osmosis & diffusion Why are osmosis & diffusion important?important?

All living things have certain All living things have certain requirements they must satisfy in order requirements they must satisfy in order to remain alive – maintain to remain alive – maintain homeostasishomeostasis

These include exchanging gases (usually These include exchanging gases (usually CO2 and O2), taking in water, minerals, CO2 and O2), taking in water, minerals, and food, and eliminating wastes. and food, and eliminating wastes.

These tasks happen at the cellular These tasks happen at the cellular level.level.

Molecules move through the cell membrane Molecules move through the cell membrane by diffusionby diffusion

A balance, or EQUILIBRIUM, must be A balance, or EQUILIBRIUM, must be maintained.maintained.