Plantcell anatomy.a.Generalizeddrawing.b,Transmissionelectronmicrographofyoungleaf cell.SeeTable 4.1fora description ofthesestructuresalonawitha listingoftheirfunctionsmicrotubule-nuclearporecentralvacuolechromatin-nuc-nucleolus-nuclearenvelopechioroplast-ribosomeactinroughERfilament.SmoothERplasmamembranecellwallCcytosolGolgiapparatusmitochondrionVintracellularspacemiddlelamellacell wallofadjacentcellFigure 1-0
Figure 1-0
OUTSIDEOF CELLWatermoleculesWater-selectivepore (aquaporin)MembranebilayerEigure I-1CYTOPLASM
⚫ Figure 1-1
lesswaterOsmosisdemonstration(highera.Athistletube,coveredatthebroad end bypercentagesolutionrisesadifferentiallypermeablemembrane,containsof solute)duetomovementa10%sugar solution.Thebeakercontainsaofwater toward5%sugar solution.b.The solute(greennetmovementofwaterhigher percentagecircles) is unableto passthroughtheto insideofthistletubeof solutemembrane,butthewaterpassesfreelythrough in both directions.Anet movementofsoluteWwatertowardthe insideofthethistletubeoccurs becausethethistle tubehas a higherpercentage ofsolute.c.In the end,thelevelofthe solution rises inthethistletube until10%morewaterhydrostatic pressure increases to the levelof(lowerosmoticpressure.percentage5%of solute)membranec. In the enda. In the beginningb.In themeantimeFigure 1-2
Figure 1-2
(a)Inhypotonicsurroundingsthe vacuole of aplant cell fillsbuttherigid cell walls preventthecell fromexpanding.Thecells of this healthybegoniaplantare turgid. (b and e)Whenthebegoniaplant isexposedtoahypertonicsolution,itscellsbecomeplasmolyzedastheylosewater.Theplantwiltsandeventuallydies.(DennisDrenner)PlasmaNucleusmembraneVacuoleVacuoleVacuolarmembrane(tonoplast)CytoplasmPlasmamembraneFigure 1-2-1(a)(b)(c)
Figure 1-2-1
OsmosisinHypertonicHypotonicIsotonicanimal and plant cells.ConditionsConditionsConditionsAnimalCellsplasmamembranec.Water exits thecell,whichb.Waterentersthecell,whicha.Nonetmovementofwatermayburst(lysis)duetoshrivels (crenation)intoandoutofthecellosmoticpressure,Plant拉蓬Cells-Cwallplasmamembranechloroplastf.Vacuoles losewater,thee.Vacuolesfillthewater,turgord.Nonetmovementof waterFigure 1-2-2cytosolshrinks (plasmolysis)pressuredevelops,andintoandoutofthecelland chloroplastsareseen inchloroplastsareseen nexttothe cell wall.thecenterofthe cell
Figure 1-2-2