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

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

Type of SolutionType of Solution

IsotonicIsotonic- a solution - a solution whose osmotic whose osmotic pressure is equal to pressure is equal to that of the cell, no that of the cell, no change will occur change will occur thus a balance is thus a balance is maintainedmaintained

a solution that a solution that causes no change in causes no change in the size of the cellthe size of the cell

Type of SolutionType of Solution

HypertonicHypertonic- a - a solution whose solution whose osmotic pressure is osmotic pressure is greater than that of greater than that of the cellthe cell

a solution that a solution that causes a cell to causes a cell to shrink because of shrink because of OsmosisOsmosis

Type of SolutionType of Solution

HypotonicHypotonic- a - a solution whose solution whose osmotic pressure is osmotic pressure is lower than that of lower than that of the cellthe cell

a solution that a solution that causes water to causes water to enter the cell, thus enter the cell, thus the cell will swell the cell will swell or even burst.or even burst.

OsmosisOsmosis In this picture a In this picture a red blood cell is red blood cell is put in a glass of put in a glass of distilled 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 .  In this case too much water case too much water enters and the cell enters and the cell swells to the point swells to the point of bursting open.  of bursting open. 

TYPES OF TRANSPORT TYPES OF TRANSPORT MECHANISMMECHANISM

Simple DiffusionSimple Diffusion The particle is The particle is transported transported through the through the membrane without membrane without the aid of the aid of permease and w/o permease and w/o expenditure of expenditure of energy by the energy by the cellcell

Passive TransportPassive Transport

Facilitated DiffusionFacilitated Diffusion The particle is The particle is transported transported through the through the permease of the permease of the membrane but w/o membrane but w/o expenditure of expenditure of energy by the energy by the cell.cell.

Passive Passive TransportTransport

Active TransportActive Transport

The particle The particle is transported is transported through the through the permease of permease of the membrane the membrane and with the and with the expenditure of expenditure of energy (ATP) energy (ATP) by the cell.by the cell.

Bulk TransportBulk TransportBulk transport involves the cell membrane making vesicles to bring materials in and out of the cell.

Two kinds of bulk transport

1. Exocytosis: moving materials OUT of the cell.

2. Endocytosis: moving materials INTO the cell.

There are 2 types of endocytosis: 1. Pinocytosis: bringing small molecules or liquids into the cell 2. Phagocytosis: bringing large molecules into the cell

ExocytosisExocytosisExocytosis is the process of exporting materials out of the cell by forming a membrane bound vesicle around the materials. The cell uses exocytosis to get rid of cell waste or to export proteins made in the cell to give to other cells.

Endocytosis-PinocytosisEndocytosis-Pinocytosis

Endocytosis is the movement of materials into the cell through

membrane bound vesicles. One type of endocytosis is called

Pinocytosis, or “cell drinking”. Pinocytosis is the movement of small molecules or liquids into the cell through bulk transport.

Endocytosis-Phagocytosis Endocytosis-Phagocytosis phagocytosis, or “cell phagocytosis, or “cell eating”. eating”.

Phagocytosis is the Phagocytosis is the movement of large movement of large molecules into the cell molecules into the cell through bulk transport. through bulk transport.

Endocytosis-Phagocytosis Endocytosis-Phagocytosis The large molecules make contact with the The large molecules make contact with the

cell membrane and the cell membrane cell membrane and the cell membrane pinches off around the molecules.pinches off around the molecules.

The lysosomes then fuse with the vesicle The lysosomes then fuse with the vesicle and break down the large molecules into and break down the large molecules into nutrients. nutrients.

Phagocytosis is how white blood cells Phagocytosis is how white blood cells engulf bacteria and break them down. engulf bacteria and break them down.

The lysosomes then fuse with the vesicle and break down the large molecules into nutrients. Phagocytosis is how white blood cells engulf bacteria and break them down.

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 Molecules move through the cell membrane by diffusionmembrane by diffusion

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