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Lecture 7

BIOL 1201 Lecture Notes - Lecture 7: Facilitated Diffusion, Membrane Transport, Passive TransportPremium


Department
Biological Sciences
Course Code
BIOL 1201
Professor
Moroney, James
Lecture
7

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BIOL1201Lecture7TransportationinCell
MembraneStructureandFunction
● Controlpointfortransportofwaterandsalutesintoandoutofthecell
● Phospholipidbilayer
● Integralproteins
● Peripheralproteins
● Selectivepermeability
TypesofMembranetransport
▪ Diffusion:passivetransportofsolutemolecules
▪ Netmovementofmoleculesdownaconcentrationgradient
▪ Ratedependsondifferenceinconcentration.Concentrationgoestoequilibrium
requiresnoenergyandnoprotein
▪ Smallandunchargedmolecules
▪ Onlyfewmolecules
▪ Facilitateddiffusionrequiresnoenergybutdoesrequiretransportproteins
▪ Activetransportrequiresenergyandatransportprotein
▪ Osmosis:diffusionofwateracrossaselectivelypermeablemembrane
▪ Waterwillalwaysmovefromhigherconcentrationofwatertolower(more
solutes)
▪ Relativetermsforsoluteconcentration:
▪ Hypotonic–relativelylowersoluteconcentrationhighwatercontent
▪ Hypertonic–relativelyhighersoluteconcentrationlowwatercontent
▪ Isotonicsamesoluteandwaterconcentrations
WaterBalanceinCells
● IsotonicSolutions
o Soluteconcentrationisthesameonbothsidesofthemembrane
▪ “Healthy”situationforanimalorplantcells
● HypertonicSolution
o Bathingsolution
o Soluteconcentrationishigherinthebathingsolution
o Watermovesoutofcelltobathingsolution
o Nothealthyforanimalorplantcells
● Hypotonicsolution
o Soluteconcentrationislowerinthebathingsolution
o Watermovesfrombathingsolutionintocell
o Notgoodforanimalcells;OKforplantcells
▪ Makeanimalcellsexplode
▪ Can’tbreakplantcellwallandcantakecertainamountofwater
TransportofSolutesAcrossMembranes
▪ FacilitatedDiffusionpassivetransportofsolutesacrossamembrane(downa
concentrationgradient)throughproteins
▪ ActiveTransporttransportofsolutesagainstaconcentrationgradientrequiringthe
▪ Transportofsolutes
o Membraneproteins(integral)thatplayaroleintransport
▪ Carriers:solutesmovedbychangesincarrierproteinconformation.
● Relativelyslowrateoftransport
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