(D)(C)(B)(A)HHHEHOUTSIDE OFCELL3HHHHHHHHCSHSHSHHHOHHHHOHSHSHHSHSHHCHDHHpiasma!membraneConcentrationgradientsfor sand H.SSHSHHHHSHCS5H5HSHHSSCYTOPLASMTheenergythatHypotheticalmodelforsecondaryactivetransport)FIGURE6.9(symbolizedbytheredarrowonthedrivestheprocesshasbeenstored inaApHsrghtinA)andisbeingusedtotakeupasubstrate(S)againstitsconcentratongrathe binding sitesontherOdient(left-handredarrow).A)Inthe)conproteinareexposed totheoutsideenvironmentandcan bindaproton(B)Thisbindingresultsinaconformationalchangethatpermitsamoleculeof Stobebound(C)Thebinding ofScausesanotherconformationalchangethatexposesthebincingsitesand theirsubstratestotheinsideofthecell(D)Releaseofaprotonandamoleculeof Sto thecell's interiorrestores the originnl conformationofthecarrierandallowsa newpumpingcycletobegin,2-4Figure 2-6(B)Antiport(A)SymnportOUTSIDE OFCELLHBHATwoexamplesofsecondaryFIGURE6.10activetransportcoupled toaprimarypro-HighLOWtongradient.(A)Inasymporttheenergydissipatedbyaprotonmovingbackintocoupledtotheuptakeofonethecellismolecule ofa substrate (e-gasugar)into(B)Inanantiporttheenerydis-the celaprotonmovingbackintetheNDatccLDycell iscoupledtothe active transportofasubstrate(forexample,asodiumion)outafthecell.nbothcasos,thesubstrateconsiderationismovingagainstitsndLowHighgradientof electrochemicalpotentialBothBAneutraland charged substrates can beElectrochomicalElectrochemicaltransportedbysuchsecondaryactivepotentialgradientpotential gradientCYTOPLASMransportprocessos.ofsubstrate BofsubstrateA
Figure 2-6 2-4 D
outside of cellThe electrochemicalgradient causes k+to enter by way of achannelproteinAn ATP-drivenpumptransports工H+out of the cellI工H+KADP+Negatively charged3ions()aretransported along withH+ into the cell.inside of cellFigure 2-5 H+ -Pump transport solutes processes
Figure 2-5 H+ -Pump transport solutes processes