EQ: EXPLAIN HOW ACTIVE AND PASSIVE TRANSPORT HELP THE CELL MAINTAIN HOMEOSTASIS.SC B-2.5EXPLAIN HOW ACTIVE, PASSIVE, AND FACILITATED TRANSPORT SERVE TO MAINTAIN HOMEOSTASIS OF THE CELL

Cell Transport

CELL TRANSPORTCHAPTER 7 SECTION 3DEFINITIONS:Equilibrium: state that exists when the concentration of a substance is the same throughout a spaceConcentration Gradient: difference in the concentration of a substance across a distance

Passive Transportdfn: movement of substances across a cell membrane without requiring energy expenditure by the cell

Types:DiffusionFacilitated DiffusionOsmosis

Passive transportParticles are said to move down their concentration gradient

It is free!

DIFFUSIONThe movement of particles from regions of higher density to regions of lower density

Also called simple diffusion

Small, nonpolar molecules pass through the cell membrane by simple diffusionEx: oxygen, carbon dioxide

SIMPLE DIFFUSION

DIFFUSION RATERate of diffusion affected by:TemperatureSurface areaConcentration gradientSize of molecule

SIMPLE DIFFUSION ACROSS a MEMBRANE

FACILITATED DIFFUSIONSame as simple diffusion (particles move down their concentration gradient) except particles require the use of a transport protein to cross cell membrane

FACILITATED DIFFUSIONBecause it requires a transport protein there is an upper limit to the # of molecules that can enter/exit a cell at any given moment(called Tmax)

Facilitated DiffusionGlucose enters cells via facilitated diffusion

OSMOSISOsmosis : the diffusion of water from a more dilute solution a more concentrated solution through a membrane that is permeable to water but not to the solute

solute: what is dissolved in solvent solvent: what dissolves the solute

OsmosisAllows cells to maintain water balance as their environment changes

http://www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swf

OsmosisWater Channels (called aquapores) in membrane to allow polar water molecules to enter/exit cellIn humans used by:Respiratory systemReproductive systemUrinary system (water conservation)Digestive systemHomeostasis of body temperature

Osmosis in Red Blood CellsHypertonic SolutionsConcentration of solutes higher than that in cytoplasmWater follows its concentration gradient and moves from ______________ to ___________Cells will _________________, called crenationhttp://www.tvdsb.on.ca/WESTMIN/science/sbi3a1/cells/Osmosis.htm

Osmosis in Red Blood CellsIf the solution is hypotonic, there is a lower solute concentration outside the cell than inside the cellWater will move _____________The cell will __________, called hemolysis.

Osmosis with Red Blood CellsIf the solution the red blood cell is in has the same concentration of water as the cytoplasm in the cell there will be _________ movement of water.This is called an isotonic solution.

Osmosis in Plant Cells

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

ACTIVE TRANSPORTDfn: the movement of substances against their concentration gradient (against the flow)Substances are moving from an area of lower concentration to an area of higher concentrationThis requires the cell to use energy (ATP)

ACTIVE TRANSPORTTWO TYPES:PUMPSVESICLESENDOCYTOSISEXOCYTOSIS

ACTIVE TRANSPORT PUMPSUse a carrier protein (like facilitated diffusion) but requires expenditure of energy

Most common pump:Na+/K+/ATP pump

Na+/K+/ATP pumpA carrier protein that uses ATP (1) to actively transport sodium ions (3) out of the cell and potassium ions (2) into the cell.

This pump keeps the [Na+] inside the cell lower so that osmosis will not cause the cell to swell with water.

ACTIVE TRANSPORTVESICLESUsed to transport molecules that are too large to fit thru a carrier protein.EndocytosisCell eating (phagocytosis) or cell drinking (pinocytosis)Cell wraps membrane around material forming vesicle which is taken into cellExocytosisFor moving material out of cellVesicle fuses with cell membrane releasing contents outside of cell

ENDOCYTOSISEXOCYTOSIS

Endocytosis Exocytosis

Active Transport Animationhttp://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/ion_pump/ionpump.html

Review Timehttp://www.learnerstv.com/animation/animation.php?ani=164&cat=biology