Difference Between Active and Passive Transport

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5/9/2017 DifferenceBetweenActiveandPassiveTransport|Definition,Types,Howitworks
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DifferenceBetweenActiveandPassiveTransport
May9,2017 •byLakna •7minread
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Main Difference – Active vs
PassiveTransport
Active and passive transport are two methods that transport
molecules across the cell membrane. A cell membrane is a
multitask unit which gives structure to the cell while
protecting the cytosolic content from the extracellular
environment. The movement of molecules in and out of the
cell is determined by the phospholipid bilayer, maintaining a
delicate homeostasis of the cell. The phospholipid bilayer is
semipermeable, allowing some molecules to freely pass the
membrane through a concentration gradient and some molecules to use special structures in order to pass the
membrane and others to pass the membrane by utilizing cellular energy. The main difference between active and
passivetransportisthatactivetransportpumpsmoleculesagainsttheconcentration gradientusingATPenergy
whereas passive transport allows the molecules to pass the membrane through a concentration gradient,
requiringnocellularenergy.
Thisarticlelooksat,
1.WhatisActiveTransport
–Definition,Types,Function,Howitworks
2.WhatisPassiveTransport
–Definition,Types,Function,Howitworks
3.WhatisthedifferencebetweenActiveandPassiveTransport
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5/9/2017 DifferenceBetweenActiveandPassiveTransport|Definition,Types,Howitworks
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WhatisActiveTransport
Active transport is the movement of molecules across the membrane against the concentration gradient with the
assistance of enzymes and usage of cellular energy. It is required for the accumulation of molecules like glucose,
aminoacids, andionsinsidethecellin highconcentrations.Twotypesofactive transport canbeidentified:primary
activetransportandsecondaryactivetransport.
PrimaryActiveTransport 
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5/9/2017 DifferenceBetweenActiveandPassiveTransport|Definition,Types,Howitworks
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During primary active transport, the presence of substances in the extracellular fluid that is required by the cell is
recognizedbythespecializedtransmembraneproteinsonthecellmembrane,whichserveaspumpsoftransporting
molecules.These transmembrane proteins arepoweredbyATP.Theprimary active transportismostobviousinthe
sodium/potassiumpump(Na+/K+ATPase),which maintainstherestingpotentialofthecell. Theenergyreleased by
thehydrolysisofATPisusedtopumpthreesodiumionsoutofthecellandtwopotassiumionsintothecell.Here,
sodiumionsaretransportedfromalowerconcentrationof 10 mM to a higher concentration of145mM.Potassium
ionsaretransportedfroma140mMconcentrationinsidethe celltoa 5mMconcentration ofextracellularfluid.The
proton/potassium pump (H+/K+ ATPase) is found in the lining of the stomach, maintaining an acidic environment
insidethe stomach. Omeprazole is a proton/potassium pump inhibitor,reducing the acid reflux inside the stomach.
During both oxidative phosphorylation and photophosphorylation of electron transport chain use primary active
transporttocreateareducingpoweraswell.Theactionofsodium/potassiumpumpisshowninfigure1.
Figure1:Sodium/PotassiumPump
SecondaryActiveTransport
Secondary active transport is powered by an electrochemical gradient. Here, channels are made by poreforming
proteins. A simultaneous movement of another substance against the concentration gradient is observed with the
secondaryactivetransport.Hence,thechannelproteinsinvolvedinthesecondaryactivetransportcanbeidentifiedas
cotransporters. There are two types of cotransporters: antiporters and symporters. Particular ion and the solute are
transported in the opposite directions by antiporters. Sodium/calcium exchanger, which allows the restoration of
calciumionconcentrationinthecardiomyocyteaftertheactionpotential,isthemostcommonexampleforantiporters.
Ions are transported through the concentration gradient while the solute is transported against the concentration
gradientbysymporters.Here,bothmoleculesaretransportedinthesamedirectionacrossthecellmembrane.SGLT2
is a symporter that transports glucose into the cell along with the sodium ions. The function of symporter and
antiporterisshowninfigure2.
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Figure2:TheactionofSymporterandAntiporter
WhatisPassiveTransport
Passivetransportisthe movement of molecules acrossthe
membranethrough a concentration gradient with no useof
cellularenergybythemovement.Itusesnaturalentropy to
move molecules from a higher concentration to a lower
concentration until the concentration becomes equalized.
Then, there will be no net movement of molecules at the
equilibrium. Four main types of passive transport are
found:osmosis, simplediffusion, facilitated diffusion, and
filtration. The simple movement of molecules across a
permeable membrane is called simple diffusion. Small,
nonpolar molecules use simple diffusion. The diffusion
distanceshouldbelessinordertomaintainabetterflow.Passivetransportacrossthemembraneisshowninfigure3.
Figure3:PassiveTransport
Duringfacilitateddiffusion, specialtransportproteinsareusedto guidethemovementofpolarmolecules andlarge
ions. These transport proteins are glycoproteins and are specific to a particular protein. The GLUT4 is a glucose
PrimaryAntibodies
ExtensiveValidation
OriGene
Over50,000Abs.Human
ProteinasAntigens.WB,IHC,
IF/ICC,IP,ELISA&Flow.
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transporterthattransportsglucosefromthebloodstreamintothe cell. It is mostly found in fatandskeletalmuscles.
Threetypesoftransportproteinsareinvolvedinthefacilitateddiffusion:channelproteins,aquaporins, andcarrier
proteins. Channel proteins make hydrophobic tunnels across the membrane, allowing the selected hydrophobic
moleculestopassthroughthemembrane.Somechannelproteinsareopenedatalltimes,andsomearegatedlikeion
channel proteins. Aquaporins allow water to cross the membrane quickly. Carrier proteins change their shape,
transportingtargetmoleculesacrossthemembrane.Facilitateddiffusionbycarrierproteinsisshowninfigure4.
Figure4:FacilitatedDiffusion
Filtrationisthemovementofsolutesalongwithwaterduetothehydrostaticpressuregeneratedbythecardiovascular
system. It occurs in Bowman’s capsule in the kidney. Osmosis is the movement of water across a selectively
permeablemembrane.Itoccursfromahighwaterpotentialtoalowwaterpotential.
DifferenceBetweenActiveandPassiveTransport
Definition
ActiveTransport:Activetransportpumpsmoleculesthroughthecellmembraneagainsttheconcentrationgradient.
PassiveTransport:Passivetransportallowsmoleculestopassthecellmembranethroughaconcentrationgradient.
CellularEnergyUsage 
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ActiveTransport:ActivetransportutilizescellularenergyintheformofATP.
PassiveTransport:Passivetransportdoesnotrequirecellularenergy.
TypesofTransport
Active Transport:Endocytosis, exocytosis, secretion of substances into the bloodstream, and sodium/potassium
pumparethetypesofactivetransport.
PassiveTransport:Diffusion,facilitateddiffusion,andosmosisarethetypesofpassivetransport.
Role
Active Transport: Active transport allows molecules to pass the cell membrane, disrupting the equilibrium
establishedbythediffusion.
PassiveTransport:Adynamicequilibriumofwater,nutrients,gasses andwastesismaintainedby passivetransport
betweencytosolandextracellularenvironment.
TransportingParticles
ActiveTransport:Ions,largeproteins,complexsugarsaswellascellsaretransportedbyactivetransport.
Passive Transport:Water soluble molecules like small monosaccharides, lipids, sex hormones, carbon dioxide,
oxygen,andwateraretransportedbypassivetransport.
Importance
ActiveTransport:Activetransportisrequiredfortheentranceoflarge,insolublemoleculesintothecell.
PassiveTransport:Passivetransportallowsthemaintenanceofadelicatehomeostasisbetweenthecytosoland
extracellularfluid.
Conclusion
Active and passive transport are the two methods of transporting molecules across the cell membrane. Active
transportpumpsmoleculesagainstaconcentrationgradientusingcellularenergy.Inprimaryactivetransport,ATPis
usedastheenergy.In secondary active transport, the electrochemical gradient is used to move molecules across the
membrane.Nutrientsareconcentratedintothecellbyusingactivetransport.Passivediffusionallowssmall,nonpolar
molecules to move across the membrane. It only occurs through a concentration gradient. Therefore, no energy is
utilizedby the process.Osmosis and filtration are also methods of passivediffusion.However,the main difference
betweenactivetransportandpassivetransportistheirmechanismsoftransportingmoleculesacrossthemembrane.
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AbouttheAuthor:Lakna
Lakna,agraduateinMolecularBiology&Biochemistry,isaMolecularBiologistandhasa
broadandkeeninterestinthediscoveryofnaturerelatedthings
Reference:
1.”Passivetransportandactivetransportacrossacellmembranearticle(article).”KhanAcademy.N.p.,n.d.Web.03
May2017.
2.”Diffusionandpassivetransport.”KhanAcademy.N.p.,n.d.Web.03May2017.
ImageCourtesy:
1.“Schemesodiumpotassiumpumpen”ByLadyofHatsMarianaRuizVillarreal–Ownwork.Imagerenamedfrom
Image:SodiumPotassium_pump.svg(PublicDomain)viaCommonsWikimedia
2.“Porters”ByLupask–Ownwork,PublicDomain)viaCommonsWikimedia
3.“Figure050202″ByCNXOpenStax–(CCBY4.0)viaCommonsWikimedia
4.“Blausen0213CellularDiffusion”ByBlausen.comstaff(2014).“MedicalgalleryofBlausenMedical2014″.
WikiJournalofMedicine1(2).DOI:10.15347/wjm/2014.010.ISSN20024436.–Ownwork(CCBY3.0)via
CommonsWikimedia
0
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5/9/2017 DifferenceBetweenActiveandPassiveTransport|Definition,Types,Howitworks
http://pediaa.com/differencebetweenactiveandpassivetransport/ 9/10
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DifferenceBetween
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5/9/2017 DifferenceBetweenActiveandPassiveTransport|Definition,Types,Howitworks
http://pediaa.com/differencebetweenactiveandpassivetransport/ 10/10