Water, Cells, Water, Cells, Membranes and Membranes and

Cellular TransportCellular Transport

HOMEOSTASISHOMEOSTASIS

survival depends on the survival depends on the ability to maintain proper ability to maintain proper conditions conditions

maintaining balance is maintaining balance is called called homeostasishomeostasis

The Cell MembraneThe Cell Membraneselective permeability-selective permeability- the cell the cell membrane allows some membrane allows some materials to enter/exit materials to enter/exit

Fluid Mosaic Model-Fluid Mosaic Model- a “collage” a “collage” of many different proteins and of many different proteins and other molecules embedded in a other molecules embedded in a fluid lipid bilayerfluid lipid bilayer

The Fluid Mosaic ModelThe Fluid Mosaic Model

http://home.earthlink.net/~shalpine/anim/Life/memb.htm

DiffusionDiffusion

diffusiondiffusion- movement of - movement of particles from an area of particles from an area of higher concentration to an higher concentration to an area of lower concentrationarea of lower concentration

the cell membrane does not the cell membrane does not limit the diffusion of waterlimit the diffusion of water

Example of DiffusionExample of Diffusion

http://osmosisproject.tripod.com/diffusion.html

OsmosisOsmosisosmosisosmosis- the diffusion of water across - the diffusion of water across a selectively permeable membranea selectively permeable membraneconcentration gradient-concentration gradient- natural natural movement from high to low movement from high to low concentrationconcentrationthe concentration gradient controls the concentration gradient controls osmosisosmosiswater will flow to the side of the water will flow to the side of the membrane where water concentration membrane where water concentration is lower is lower

Osmosis PrefixesOsmosis Prefixes

isoiso- the same- the same

hypohypo- less- less

hyperhyper-- more more

You have 3 types of You have 3 types of solutions: isotonic, solutions: isotonic, hypotonic, and hypertonichypotonic, and hypertonic

Osmotic SolutionsOsmotic Solutions

isotonicisotonic- same amount of water - same amount of water inside and outside the cellinside and outside the cell–water enters and exits at the same ratewater enters and exits at the same rate

hypotonichypotonic- less water inside the - less water inside the cellcell–water enters the cellwater enters the cell

hypertonichypertonic- more water inside the - more water inside the cellcell– so water exits the cellso water exits the cell

http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htmhttp://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

Now you know why it’s Now you know why it’s wrong to put salt on slugs….wrong to put salt on slugs….

Passive TransportPassive Transport

Any type of transport that does Any type of transport that does NOT require energy (ATP)NOT require energy (ATP)movement is movement is withwith the the concentration gradientconcentration gradienti.e.- diffusion of water, i.e.- diffusion of water, facilitated diffusionfacilitated diffusion

Passive Transport cont.Passive Transport cont.facilitated diffusion-facilitated diffusion- passive passive transport of materials across transport of materials across the membrane using the membrane using transport proteinstransport proteins–transport proteinstransport proteins facilitate facilitate

(assist) molecules across the (assist) molecules across the membranemembrane–movement is movement is withwith the conc. grad. the conc. grad.

Active TransportActive Transport

moves materials moves materials againstagainst a a concentration gradientconcentration gradient

counteracts the force of counteracts the force of diffusiondiffusion

requires energyrequires energy from the cell from the cell

transport proteins are involvedtransport proteins are involved

Transporting Large ParticlesTransporting Large Particlesendocytosis-endocytosis- a cell surrounds and a cell surrounds and takes in material from its environmenttakes in material from its environment–the material does not pass directly the material does not pass directly

through the membranethrough the membrane

exocytosisexocytosis- reverse of endocytosis- reverse of endocytosis–materials are expelled from the cellmaterials are expelled from the cell

Endo- and ExocytosisEndo- and Exocytosis

http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html