华南师范大学：《植物生理学》课程教学资源（英文教案）Chapter Two Mineral Nutrition of Plant

Chapter TwoMineralNutritionofPlantIAbsorptionof mineral elements byplant cells1Biological membrane(1)Nature: selectivity permeability(2) Composition:①protein30~40%②phospholipid40~50%carbohydrate,10%~20%sterol? Protein include extrinsic (peripheral protein )intrinsic protein (integral protein )and a anchoredprotein. Their roles are tansport, structure.and transfer message etc.·Phospholipid includepolar head group composition:cholin,phosphateand glycerd.(naturewater-loving or called hydrophilic) and nonpoplar tail group (14~24 carbon atoms long-chainfattyacids.Nature:water-fearingorcalledhydrophobic)(3) Structure·Phospholipids consist of a double layer (bilayer)· Proteins associated with lipid bilayer are of three types: intrinsic (integral),extrinsic( peripheral),and anchored. Integral proteins are embeded in the lipid bilayer, most integral proteins span theentire width of the phospholipid bilayer.They serve as ion channels and certain receptors etcperipheral protein are bound to membrane surface by noncovalent bonds, such as ionic bonds orhydrogen bonds.Peripheral proteins serve a variety of functions in the cell. Anchored protein arebound to the menbrane surface via lipid molecules (fatty acid-anchored protein and glycosyIphosphatidylinositol anchored protein and prenyl lipid-anchord protiens)Fluid-mosaic model:

Chapter Two Mineral Nutrition of Plant I Absorption of mineral elements by plant cells 1 Biological membrane (1) Nature : selectivity permeability (2) Composition: ①protein 30~40% ②phospholipid 40~50% ③carbohydrate , 10%~20% ④sterol ·Protein include extrinsic (peripheral protein ) intrinsic protein. (integral protein )and a anchored protein. Their roles are tansport , structure.and transfer message etc. ·Phospholipid include polar head group composition: cholin, phosphate and glycerd. (nature: water-loving or called hydrophilic ) and nonpoplar tail group (14~24 carbon atoms long-chain fatty acids. Nature: water-fearing or called hydrophobic ) (3) Structure ·Phospholipids consist of a double layer (bilayer) ·Proteins associated with lipid bilayer are of three types: intrinsic (integral),extrinsic( peripheral), and anchored. Integral proteins are embeded in the lipid bilayer, most integral proteins span the entire width of the phospholipid bilayer. They serve as ion channels and certain receptors etc. peripheral protein are bound to membrane surface by noncovalent bonds, such as ionic bonds or hydrogen bonds. Peripheral proteins serve a variety of functions in the cell. Anchored protein are bound to the menbrane surface via lipid molecules (fatty acid-anchored protein and glycosy lphosphatidylinositol anchored protein and prenyl lipid-anchord protiens) Fluid-mosaic model:

hosphateHydrophilireg/oCellvslyceroPlasmcarbohwOutsideof celleqionohpioiamHydrophobiregiorHydrophillPhosphatidylcholineCytoplasmIntegralPeripheralCholineproteirorotei(8)GalactoseAdiDrimarwallsFiGURE2.1(A)Theplasmamembrane,endoplasmicreticerendomembranesofplant cells consist ofPhosphatidyicholineGalactosylglycerideibedded in a phospholipidbilayer. (B)This transctron.micrographshowsplasmamembranesinllaotmOspace,ivnaoenhevoengandSteer1992.Thetypes andmechanisms of soluteabsorptionbyplantcells.(1) Types:①lon channel transport②lon pump transportCarrier transportPinocytosis(2)Mechanisms@Ion channel transport major theory:There are ion channels (integral protein )inplasmamembrane.② Ion channel is activated by ion concentration gradient and membrane potential gradient(Calledelectrochemicalpotentialgradient)③Ion channel isopened@ ons intothecellfollowing electrochemical potential gradient

2. The types and mechanisms of solute absorption by plant cells. (1) Types: ①Ion channel transport ②Ion pump transport ③Carrier transport ④Pinocytosis (2)Mechanisms ① Ion channel transport major theory: There are ion channels (integral protein )in plasmamembrane. ② Ion channel is activated by ion concentration gradient and membrane potential gradient (Called electrochemical potential gradient ) ③ Ion channel is opened ④ Ions into the cell following electrochemical potential gradient

Transported moleculeOOChannelCarrierPumpproteinproteinPlasmaHighmembraneEnergyLowElectrochemicalSimplediffusionpotentialgradientPassive transportPrimaryactivetransport(in the direction of(against the directionelectrochemicalgradient)ofelectrochemical gradient)FIGURE2.2Three classes ofmembrane transport proteins:channels,carriers,andpumps.Channels and carriers canmediatethepassivetransportof solutes acrossmembranes (by simplediffusion orfacilitateddiffusion),downthesolute's gradientofelectrochemical potential.Channelproteinsactasmembranepores,andtheirspecificity is determined primarilyby the biophysical properties of the channel.Carrierproteinsbind thetransportedmoleculeononesideof themembraneandrelease it on the other side.Primary active transport is carried out bypumps anduses energy directly,usuallyfrom ATPhydrolysis,to pump solutes against theirgradientofelectrochemicalpotential.Kinds of ion channelThereareK+ClCa2+,NO,channelsK+channel:ForexampleCompositionTwo a-subunitsVoltage gateMajor partSelectivityfilterTwo β -subunits, Regulatoryα -subunitTransport speed: 107-108 ions ·s-Distribution:1K+channel.15Hm-2inplasmamembrane250k+channel·4000μm-2Guard cell plasmamembrane

Kinds of ion channel There are K+,Cl-,Ca2+ , NO3 − channels For example K+ channel: Composition Two α-subunits Transport speed: 107 -108 ions·s -1 Distribution: 1 K+ channel·15 µm-2 in plasmamembrane. 250 k+ channel·4000 µm-2 Guard cell plasmamembrane Voltage gate Selectivity filter Major part Two β-subunits, Regulatory α-subunit

②CarriertransportS+C-+S·C-Sinto the cellUniportcarrierFollowingelectrochemicalPotential gradient transport.H+Kind of carrier+C-H+: A· C-H*·Ainto the cellSymporterAH*(outside)H+ into the cell+C-H·B·CAntiporterB(inside)B out of the cellSpeed: 104-105 ions : s!(A) Symport(B) AntiportOUTSIDEOFCELLAOBFIGURE2.3TwoexamplesofsecondaryactivetransportcoupledtoaprimaryproHighLowton gradient. (A) In a symport,the energydissipatedbya proton movingback intothe cell is coupled to the uptake of onemolecule ofa substrate (e.g.,a sugar)intothe cell. (B) In an antiport, the energy dis-sipatedbyaprotonmovingbackintothecell is coupled tothe activetransport of asubstrate (forexample,a sodium ion)outof the cell, In both cases, the substrateHighunderconsideration ismovingagainstitsLowgradientof electrochemical potential,BothBAOBneutral and charged substrates can beElectrochemicalElectrochemicaltransported by such secondary activepotential gradientpotential gradientCYTOPLASMofsubstrateAofsubstrateBtransportprocesses③lonpumptransportproton pump (H*-pump)KindCalciumpump(Ca2*-pump)ProtonpumptransportMajor theoryA plasmamembrane H-pumpATPase is effected by H+ cytosol..ATP hydrolysis.. Uses the energy released to transport H+ (hydrogen ions) out of the cell·Establishesanelectrochemical potential gradient.Allows (Causes)K+ and other positively charged ions to cross the membrane via a channelprotein.· Negatively charged (I)ions are transported along with H+ into the cell

② Carrier transport Kind of carrier Uniport carrier S+C→S·C→S into the cell Following electrochemical Potential gradient transport. Symporter H+ A +C→H+·A·C→H+·A into the cell Antiporter H+ (outside) B(inside) +C→H+·B·C H+ into the cell B out of the cell Speed: 104 -105 ions·s -1 ③Ion pump transport proton pump (H+ -pump) Calcium pump(Ca2+ -pump) Proton pump transport Major theory · A plasmamembrane H+ -pump ATPase is effected by H+ cytosol. · ATP hydrolysis. ·Uses the energy released to transport H+ (hydrogen ions) out of the cell. ·Establishes an electrochemical potential gradient · Allows (Causes ) K+ and other positively charged ions to cross the membrane via a channel protein. ·Negatively charged (I- )ions are transported along with H+ into the cell. Kind s 3

outside of cell2.Theelectrochemicalgradient causes Kto enterbywayofachannel protein.1.AnATP-drivenpumptransportsHHO0H*outofthe cell.HHGHHHH+H+IH上店THIMADP+ATFH3.Negatively chargedions()are trans-Hported along withH+intothe cellinsideofcellModel formineraltransport.Figure 2.4When minerals aretransported across theplasmamembrane,anATP-drivenpumpremoveshydrogenions fromthecell.Thisestablishes anelectrochemical gradientthatallowspotassium(K)andotherpositivelychargedionsto crossthemembraneviaachannel protein.Negatively charged mineral ions (I)can cross themembranebywayofacarrierwhentheyhitcharidewithhydrogenions (H"),whichare diffusingdown theirconcentration gradient.@PinocytosisSubstances (lon or mocecule adsorb in the plasmamembrane.)·Plasmamembranefold·Forma vescle·VescleintothecytosolorvacuoleFigure2.5PinocytosisSummary:

④Pinocytosis · Substances (Ion or mocecule adsorb in the plasmamembrane.) ·Plasma membrane fold. ·Forma vescle ·Vescle into the cytosol or vacuole. Figure 2.5 Pinocytosis Summary:

SymportersAminoSucroseHHt,Na*acidH+KAntiporterPO.HtCYTOSOLNatPH7,2NOjAE=-120mVPlasmaEffluxmembranecarrierAntiportersSucroseMg2+HexoseCd2+ADP+PSucroseCa2+fyeHATPH+K3 H*H+.PC-Cd2+中H+CATPPH 5.5pumpsH+NatADP+PZE=-90mVABCEADP+PATP>ABCAnthocyaninVACUOLEtransportersHsGSTpH 5.5pumps2H+-ATPABCETonoplastATPADP+PAnions,手ADP+PcationsPPATPCa2tADP+Ppumpca人2PADP+P*Ca2+FastvacuolarSlowvacuolar(FV) channel(SV)channelIP3Anions(malate2-CF,NO)ChannelsOUTSIDEOF.CELLinwardInwardrectifyingrectityingCa2+fOutwardOutwardrectifyingrectifyingChannelsFIGURE6.11Overview of the various transport processes on the plasmamembrane and tonoplast of plant cells.Figure2.6Varioussolutestransportprocesses

Figure 2.6 Various solutes transport processes