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Bio-ScoreTeocher'sEdition2008

#ffie%#The semi-permeabilityof the membrane The size and polarityof the molecules The concentrationgradientof the solution

Movementof Substances acrossthe Plasma illlembrane

is furtherdivided nto

Typesof solution

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1.

2.

Bio-ScoreTeocher'sEdition 0083.1 MOVEiIENTACROSSTHE PLASMA IIEMBR.ANE

Learning Outcomesr State the substancesequiredby living cells and substanceshat have to beeliminatedrom cells. Explain he necessityor movement f subshncesacrosshe plasmamembrane. Describehe structureof the plasmamembraner Describehe permeability f the plasmamembrane. Explain he movement of soluble substancesacross the plasma membmnethrough he process f passiveransporto Explain he movement of water moleculesacross the plasmamembrane byosmosis. Explain he movementof substances cross he plasmamembrane hrough heprocess f active' mnsportr Explain the processesof passive tmnsport and active transport in livingorganisms, singexamples. Compare nd contrastpassiveransportand active ransportSubstanceshat are requiredby cellsare: water, .9&lg9!!and gt!e!E and substancesobe eliminatedrom cells are carbon dioxide, gIgA andgdg^gglS!Thenecessityor he movement f substances cross heplasmamembrane

. Obtainnutrientsor metabolism.r Eliminateoxicwasteproductsr Maintain oncentrationf ions hatare suitableor the activities f the cell.n Maintainhe optimalpHvalue

The movement f substancesn and out of the cells s regulated y plasmamembraneThe plasmamembranesthe boundaryhat separateshe ivingcell rom tssurrounding.S.J. Singer nd G.Nicolson1972)proposed membranemodelcalled he fluid masapmodel.Thefluid-mosaic odeldescribeshe plasmamembrane s dvnamic,with he protein ndphospholipid oleculesree o movewithin he membrane.

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Bio-ScoreTeocher'sEdilion2O0BThe Structure of the PlasmaMembrane1. Completehestructure f plasmamernbrane nd abel he structure sing heterms n thebox below:

Pore pore proteinphospholipidsilayer

glycoprotein carrierproteinhydrophobic ail

cholesterolhydrophilic ead

glycoproteinPhospholipidsbiiayer

Carrier Xprorern Poreprotein

2.J,

4.

Plasma membrane, according to the fluid-mosaic modelphosoholipids and protein.Eachphospholipid olecule onsists f twoparts:

a. A polarhead hatgives t hvdrophilic property.b. A pairof non-polaraits hatgives t hvdrophobic- roperty.'ln plasmamembranes, hospholipidsrrange hemselvesntwo ayers bilayer).a- the hydrophilic eadsof the outer ayer ace he extrcellular luid.b. the hydrophilic eadsof th?.lllly layer ace he cvtoplasmic luid.

Thephospholipid ilayeractsas a banierwhich solateshe wo sidesof the mernbrane.Thephospholipid ilayeralsocontains holesterolwhich inks he attyacids ogether.

I _---_ll9hofesterollmakes lasmamembrane.btable,trong,more lexibleand lesspermeableto lvater-solubleubstances uchr@

Bothproteinsare referredas try,rt proteins.9. Somemembrane roteinshat havecarbohydratesftached o themare called

glvcoproteins,

is composed mainly of

5.6.7.

8.

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Bio-ScoreTeocher'sEdition2S8The Permeabilityof the PlasmaMembrane1. Themembranessaid o be mpermeablef it preventshe passage f all molecules.2. The plasmamembranes, however, electively errneable r semi-penneable hismeans

that certainsubstances an moveacross he plasmamembranereelywhile otherscannot.3. The size and polaritv of moleculesdetermine he movementof moleculesacross heplasmamembrane.

Structure f plasmamembrane Exarnples f substancbshat move acrossthe plasmamembranePhospholipidbilayer - lipid-soluble olecules:attyacids,glyggro!andvitaminA,_pr-E(- non-polarmolecules gJJgg!!andcarbondioxide

- smallmolecules: aterPoreprotein Smallwater*soluble moleculesand ;op5' f. Na+. C&Carrierprotein Largewater-solublemofecules:qlucose and amino acids

The movementof solublesubstancesacross the plasmamembrane hrough the processof passive transport The movement of suchsubstances across themembrane according toconcentrationgradients withoutany nputof energyby the cells

Oxvqen, carbon dioxide andlipid-soluble rnolecules

qlucose.aminoacids

Small water-soluble moleculesand iongl{t-t{Al-CaE

Movementof molecules r io-nsfrom a region of hiqher.concentration o a region oflowerconcentration, oingdowna concenfrationradientuntilanesuilibrium s achieved.

The movement of molecules aided bYtransport protein down their concentrationgradient without using ggggqy until anesuilibrium is achieved.

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Bio^-Scoreeocher's dilion 008Facilitated diffusion through aporc proteina. Pore proteins are transporters that are always open. Small dissolved particles

especially ons can move across the plasma membrane hrough his pores.b. Pore proteins have specific' through.

shapes and chargesthat only allowspecific ons to pass

aol'===.*.-.- 'on" Highconcentration

lowconcentration

oliltill IIITITIxtli Lr.poreproteinFacilitated diffusion through a carrier protein

High concentration

low concentration

'.i.:rufforil]I)o!:

oo) (Oll

t IoIililt illTIIliltIIll illlliltmIIIllr oaooo30clIItr1, Molecules uchas glucose, mallproteins ndarninoacidsmove owards.the inding itesot

specific arrierproteinand bind hemselveso the specific sites.2. Thecanierprotein hangestsshaoe to allow he moleculeso pass hrougho the otherside

of heplasmamembrane3. Theprotein esumests oriqinal shape.

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htl? tt \' ' gV"t'ra'l' *t r" r nt ir'rl ' 7 m

Bio-ScoreTeocher'sEdition 0O8The movementof watermoleculesacross the plasmamembraneby osmosis

1. Osmosis sthe net movement f water moleculesroma regionof theirhiqherconcentration o a region of their lower concentration through a serni-pgrngggp!9.membrane.

. Osmosis s importanto cellsbecause ellsneedadequatewater o functionwell .

Semi-pemreablemembraneWatermolecules Solutemolecule\ o"c: :"o"Joo, : : : .

Net movement of water moleculesLowconcentrationf solutemoleculesHighconcentrationfwatermoleculesLowosmoticpressure

highconcentration f solutemoleculeslow concentration f water moleculashighosmoticpressure

of substances across the plasma rnembranethrough the process ofctive ransport1. Active transport is the movementof molecules or !g$s from a region of lowerconcentrationo a regionof hiqherconcentrationcross he plasmamembrane ith he useof cellular nergv

. Besidesusing energy in the form of ATP that is generatedduring respiration, ctivetransport lsorequired arrier protein.

3. The carrierproteinhas an agtive site whichbindswith a particularmoleculeor ion andanotheractivesitewhichbinds o theATP molecules.

. Active ransport esultsn the accumulationof or eliminationof moleeules r ions rorn hecells .e equilibrium tate s neverachieved.

5. Carrierproteinsnvolvedn active ransport re oftencalledpump because heyare ust ikewaterpumpwhichuseenergyo movewateragainst ravitv

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6. ln animal ell, heconcentrationf p#fFif:T.... ions r.{.r.4.f.-.,he cell s always igher hanihe concentrationt',rtfii.f.. the cell,while he concentrationf sp.#:t:t.. onsoutside hecell salways i3h.?.1...,han hconcentrationnsidehecells.

7. Carrier roteins re called #l.YY..:p#fi9.Y pump hat help o maintainhe concentrationgradientsypumpingodiumons utof hecellandpotassiumons nto hecell.

8. Inplant ell, here ssodium,pumpechanismnmangroveoot.

1. Thesodiumonsapproachhecgyrif.f..pt:*?L..... Thecarrier rotein asa s.f.t9...or hesodiumons ndanother ite o bind heATPmolecules.

2. Thecarrier rotein in#... thesodiumons.TheATPmoleculess split nto f.?....andph.el?.h3.19......hesplitting fATP eleases l\9T99....o the carrier rotein.

3. Energyrom heATPchangesheshg.?.*... f thecarrier roteino releasehesodiumonsoutsidehecells.

4. Thecarrier roteinurn o origill*I... shape

Themechanism f ActiveTransport or Sodium onsoutside of cell

Sodium'"" -@-@*@@High oncentrationof sodiumons

Carrierprotein

lowconcentrationfsodiumons ATP tADPd.3.

Carrierprotein

@ Ilnsideof cel l

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Theprocesses f passive ransportand active ransport n livingorganism

PROCESSES EXAMPLE EXPLANATIONSimplediffusion

Gaseous xchangenthe alveoliand bloodcapillaries

- the concentrationf oi1Y.9fl..n the alveolis hiah*rthan tsconcentrationn hebloodcapillaries.

- oxygenn thealveoli iffusesnto he bloodcapillaries

- the concentrationf cE*gn.d.t?*i4.f.....n thebloodcapillariess,hiah.?L..han tsconcentrationn healveoli.

- carbondioxide iffusesrom he blP.?i.... .s.f':tt.q:l:.:of the ungsnto healY.f.?$....

Facilitateddiffusion

Absorption fdigestedood n hevillus

- the concentrationf glY.c.?L.nd a.'ytll\?..acid.'is n he leum shIe!^.':f..han n he blood apillariesof he villus

- glucose ndamino cids hatdiffusento heepithelialellsareabsorbed irectlynto he bloodcapillariesf thevilli.

Osmosis Absorptionof waterby root hairs of aplant. Soi lpart icle

llRoot hair

lon intake byhairs f a plant

root

- the'soilhasa higher oncentrationf watercomparedo thecells.*P.,...of roothairs.

- therefore, atermoves nto hevacuoles f roothair cellsby oxTf.?l.s-,

Activetransport

- theconcentrationf onsandmineral alts n hecellsap shrgffl'..comparedo thesurroundingoil.

- energyrom he ATPmoleculess used o transferthemineralonsagainsthe concentrationradient'throughhecellmembranento herootcell.

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Gompareand contrast passivetransport and active transportBio-Score eocher'sEdiii'rn2008

Active transportassivetransport -_--l @Both occurs through plasmamembrane

Themovement f substancesfollows he concentrationgradient

Concentration gradient Substancesmoveagainstthe concentrationradient.

Cellular nerqy s not required Cellularenergy Cellular nergy s required

Theprocess ontinues ntiladynamic quilibrium isreached

Outcomes of the process Theprocessesultsn theaccumulationf orelimination f substancesfrom he cell.

Gan take place in livingcellsornon-livingphysicalcondition

Location occurs only takes place in livingcells

Bio-BrainFigure howsa comparison f ionsconcentrationn pondwaterand n the cell sapof Nirel/a p.Whichprocesscauses he ion concentrationnNitellasp" o be higher han hat in pondwater?

P: OsmosisQ: Plasmolysis

($J Active ransportS : Passive

Concentrationsof ons I Pond ater$lCell ap f [ireiia p.

[/ineralcns, :1tL1-t ,

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Bio-ScoreTe'rcher'sEdition20OB

3.2 MOVEMENT F SUBSTANGESCROSS HEPLASMAMEMBRANENEVERYDAYLIFE.

Learning Outcomes. Explainwhat hypotonic,hypertonic nd sotonic olutionare.. Explainhe effectsof hypotonic,hypertonic nd isotonic olutionon plantandanimalcells. Fxplainplasmolysis,eplasmolysis,aemolysis ndcrenation. Designan experiment o determine he concentrationof externalsolutionwhich s isotonico the cell saP. Makean inference n the concentration f cellsap n plant issues. Relate the movement of substancesacross plasma msxbrane withconcentrationradientr Explain he phenonrenon f wilting n plantsusingexamples. Fxplain he preservaUonf food usingexamplesEffects of different types of solutlon on plant and animal cells

Table shows what wouldtypes of solution.

hibpen to an animalcell and plantcellwhen imrnersedn 3

PLANT CELL(EPTDERMTSELL)

- waterdiffuses ntoandout of thecell at equal ates

- the cell retainstsnormal izeand shCpe

- the flow of water into and out of thecell is balanced

- cell does not change shaPeor size- vacuolemaintains he normalsize

waterwater*l. ' ' - ' .1lr l&*.--. l :s. i - . . . . . ' ' l ; i +. i . .a f-- *- - -* -- " : ' 'kL, l .+-F

I hree of solutron reHypotonicsolution lsotonic olution Hypertonicolution

A solution in which theconcentration of soluteoutside he cell s lower thanthe concentration f soluteinsidehe cell

A solution n which he soluteconcentrations equal to thatof the cytoplasmicluid.

A solution in which theconcentrationof solute in thesolution is hiqher than theconcentrationof solutewithinthe cell.

ANIMAL CELL(RED BLOOD CELL) IsotoIT

ITG

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Bio-ScoreTeocher'sEdition 2008ANIiilAL CELL

(RED BLOOD CELL)so|.uTtoN PLANTCELL

(EPTDERMTSELL)- waterenters he cell by osmosis.the cell expandsandSrsrS- haemolvsis akesplace Hvpoton

IG

- waterdiffusesnto hevacuole yosmosis- vacuole xpands ndswells up- thecelldoes ot burst ecause f the igidcell wall

- the vacuole ainswaterand he plasmamembrane ushes gainst herigidcellwall-

- thecellbecomesurqid- )14\- theswelling fa plantcellcreates urqor I-^pressurgwithin he celt- t'uatgc- turgorpressures mportanto plantcells nsupportingndmaintainingheshape f thecells.

I,",;:-- **.- { '-t-- -:'.-. l r , { - ' . - iV '' . : waferi l r . | - ,n i*t,. j* '- | g,:. : . . . r i . .'* l ' -" :"- '

I- water eaveshe cellbv osmosis

-rild^ v^+- the cellshrinksup

- the plasmamembrane rinklesup

- crenation akesplace

HvpertonIIc

- waier diffusesout of the.vacuoleby osmosis- vacuoleand cytoplasm hrink- plasmamembranepullsaway fromth e cellwall i:"u.a1 ).g"\- the cell becomes flaccid /

- this process s called plasmolvsis- a plasmolysedplantcellcan becometurgid again by immersing he cell in ahvpotonic solution.

- the cell have undergonedeolasmolvsis.- -==--l=if'T; Irl-=-r;i'i l 1 . " t .1 ' ! \ l i waterl ' " / . . . " -- ' t ' . : , . ' . j irl::.__-- _ | :1i:i.,'+

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Bio-ScoreTeocher'sEdition @8e Effectsand Applicationsof Osmosis n EverydayLife

plants caused by the excessive use of chemiedfertilisercWilting n plantss usually ausedby the excessive seof fertilisers-

uch as potassiurnnitrate which'are dded o the soildissolven the soilwater.This makes he soilwatermore concentrated nd hvqer.tonic o the cell sap of the plantroots.

diffuses rom the cell sap into the soil by osmosis, causing he cells to beplasmolvsedA wiltingplanteventually ies f it is not wateredmmediately.

offood using salt and sagarsuch as mushrooms, ruits, vegetables and fish can be preserved onger using sattand sugar

These preservativeswill make the solution outside the food more bypgdg.llig compared tothe contentsof the food,The hypertonicsolution causes watg,f o leave the food by osmosis. -

cells in the food substancesbecome dehvdrated.such as bacteria and funqi also lose water by osmosis to the surrounding

solution and will eventuallydie. Therefore, ood will have a longer shelf life.3 APPRECIATINGHE MOVEMENT F$UBSTANCES CROSS HE PLASIIIAMEMBRANE

. Explainhe necessityor the rnovement f substantesacross he plasmamembmnewhich occursn a continuous nd controlledmanner or the survivalof a cellmovementof substancesacross the plasma membrane n a continuousand controlledmanner is

important or the survivalof a cell.By being semi-permeable o different substances, the plasma membrane acts as a "gatekeepefregulatingwhat goes in and out of the cell.

plasma membranealso acts as a barrier between the content of the cell and the sunoundingenvironment.

there is a defect in the plasma membrane, many living processeswhich are essential o a cellcannot be carried out. Nutrients such as glucose and amino acids from the external environmentcannot enter the cell and toxic waste productscannot be eliminated rom the cell,Thus, the proper unctioningof the plasmamembrane s important o our health-

maintain he proper functioningof a plasma membraneand a cell as a whole, it is essentiatthatwe take good care of our food and water intake.

sufficientwater everydaywill help to hydrateour body cells as well as regulate he osmoticpressure f the blood.Thiswillprevent he bodycells rom beingdehydrated.

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