Diffusion & OsmosisDiffusion & Osmosis

Define Diffusion Define Diffusion

DiffusionDiffusion

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

Draw a diagram of an Draw a diagram of an example of diffusion we example of diffusion we

saw in class.saw in class.

Draw a diagram of an example of Draw a diagram of an example of diffusion we saw in class.diffusion we saw in class.

See an animation of See an animation of diffusion here:diffusion here:

http://http://lewis.eeb.uconn.edu/lewis.eeb.uconn.edu/lewishome/applets/lewishome/applets/

Diffusion/diffusion.html Diffusion/diffusion.html

Define osmosisDefine osmosis

OsmosisOsmosis

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

Define osmosisDefine osmosis    Water moves from a high Water moves from a high

concentration of water concentration of water (less salt or (less salt or sugar dissolved in it) sugar dissolved in it) to a low to a low concentration of water concentration of water (more salt or (more salt or sugar dissolved in it)sugar dissolved in it)..  This means   This means that water would cross a selectively that water would cross a selectively permeable membrane from a dilute permeable membrane from a dilute solution (less dissolved in it) to a solution (less dissolved in it) to a concentrated solution (more concentrated solution (more dissolved in it).dissolved in it).

http://www.usd.edu/~bgoodman/Osmos.htm

http://www.usd.edu/~bgoodman/Osmos.htm

Define osmosisDefine osmosis

Define osmosisDefine osmosis In this picture a red blood In this picture a red blood

cell is put in a glass of cell is put in a glass of distilled water (all water distilled water (all water with no salt or sugar in it).  with no salt or sugar in it).  Because there is a higher Because there is a higher concentration of water concentration of water outside the cell, water outside the cell, water enters the cell by enters the cell by OSMOSISOSMOSIS.  In this case too .  In this case too much water enters and the much water enters and the cell swells to the point of cell swells to the point of bursting open.  In the end bursting open.  In the end pieces of cell membrane pieces of cell membrane are left in the water. are left in the water.

http://www.usd.edu/~bgoodman/Osmos.htm

See an animation of See an animation of osmosis here:osmosis here:

http://http://lewis.eeb.uconn.edu/lewis.eeb.uconn.edu/lewishome/applets/lewishome/applets/

Osmosis/osmosis.html Osmosis/osmosis.html

Define selectively Define selectively permeable membrane permeable membrane

Selectively Permeable MembraneSelectively Permeable Membrane

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

Materials pass through Materials pass through porespores in the in the membranemembrane

For more information on For more information on diffusion & osmosis, click diffusion & osmosis, click

here:here:

http://edtech.clas.pdx.edu/http://edtech.clas.pdx.edu/osmosis_tutorial/default.html osmosis_tutorial/default.html

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

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

All living things have certain requirements All living things have certain requirements they must satisfy in order to remain alivethey must satisfy in order to remain alive – – maintain 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 level.These tasks happen at the cellular level. Molecules move through the cell Molecules move through the cell

membrane by diffusionmembrane by diffusion

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 requirements they must satisfy in order to remain alive. These include order to remain alive. These include exchanging gases (usually CO2 and exchanging gases (usually CO2 and O2), taking in water, minerals, and O2), taking in water, minerals, and food, and eliminating wastes. These food, and eliminating wastes. These tasks ultimately occur at the cellular tasks ultimately occur at the cellular level, and require that molecules level, and require that molecules move through the membrane that move through the membrane that surrounds the cell. surrounds the cell.

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

This membrane is a complex This membrane is a complex structure that is responsible for structure that is responsible for separating the contents of the cell separating the contents of the cell from its surroundings, for controlling from its surroundings, for controlling the movement of materials into and the movement of materials into and out of the cell, and for interacting out of the cell, and for interacting with the environment surrounding with the environment surrounding the cell. the cell.

OsmosisOsmosis If environment is:If environment is:

– Hypertonic:Hypertonic: MORE SOLUTES outside cellMORE SOLUTES outside cell MORE WATER IN CELLMORE WATER IN CELL over time, cell loses water and shrinksover time, cell loses water and shrinks

– Isotonic:Isotonic: “ “Iso-” means environment “=” cellIso-” means environment “=” cell No change in cell volumeNo change in cell volume

– Hypotonic:Hypotonic: LESS SOLUTES outside cellLESS SOLUTES outside cell LESS WATER IN CELL, more solutes in LESS WATER IN CELL, more solutes in

cell.cell. over time, cell gains water over time, cell gains water HYPO—HIPPOHYPO—HIPPO

OSMOSISOSMOSIS

HYPHYPERERTONICTONICHYPHYPERERTONICTONIC ISOISOTONICTONICISOISOTONICTONIC HYPHYPOOTONICTONICHYPHYPOOTONICTONIC

OSMOSISOSMOSIS

HYPHYPERERTONICTONICHYPHYPERERTONICTONIC ISOISOTONICTONICISOISOTONICTONIC HYPHYPOOTONICTONICHYPHYPOOTONICTONIC

Normal RBCs

Isotonic SolutionIsotonic Solution

OsmosisOsmosis

Equal movement of waterinto and out of cells

Net movement ofwater out of cells Net movement of

water into cells

Shriveled RBCs

Swollen RBCs

Hypertonic SolutionHypertonic Solution Hypotonic SolutionHypotonic Solution