(B)Active CDK(A)Mitoticphasestimulatesmitosis1-eserMcyclinedegradationPP淘OCDKOMitosisInactiveMG2CDKInactiveMGCDKCDKDKPPATPSQADPADPINTERPHASEMitotic2ATPEcyclin (CM)6(A)Diagramofthecell cycle.(B)FIGURE1.26Diagramoftheregulation ofthecell cyclebyCDKG,cyclin (Cg.)InactiveCDKcyclin-dependentproteinkinase (CDK).DuringG,CDKisinitsinactiveform.CDKbecomesactivatedbybindingtoGcyclin(Cc)and byCDKbeing phosphorylated (P)at theactivation site.The activatedP?CDK-cyclincomplexallowsthetransitiontotheSphase,AtActivationInhibitorythe end of the Sphase,the G, syclin is degraded and theOsitesiteCDK is dephosphorylated, resulting in aninactive CDKGCyclindegradationThecellentersG.DuringGa,theinactiveCDKbindstotheActiveCDKmitotic cyclin (CM),orM cyclin.Atthe same time,thestimulatesDNACDK-cyclincomplexbecomesphosphorylatedatbothitssynthesisactivationand itsinhibitorysites.The CDK-cyclin complexis still inactivebecausetheinhibitorysiteis phosphorylated,Theinactivecomplexbecomes activated whenthephosphateis removed fromtheinhibitorysitebya proteinphosphatase.Theactivated CDK then stimulates thetransi-tionfromG,tomitosis.Attheend ofmitosis,themitoticFigure 10-2cyclin is degraded and the remaining phosphate at the acti-vation site is removed by thephosphatase, and the cellentersG,again
Figure 10-2
cell wallcellulosefibril200nmmicrofibrilplantcellFigure 10-5OHOHOHOHCC2OHOHOHOHOHOH8cellulosemicrofibrilOHOHOHOHhydrogenbondOHOHOHOHOOHOHOHOHCellulose fibrils.Inplantcell walls,eachcellulosefibril containsseveralmicrofibrils.Eachmicrofibril containsmanypolymersofglucosehydrogen-bondedtogether.Threesuchpolymersareshown
Figure 10-5
H+H+H+IAA+.H+ABP1H+ATPATPATPATPIAAATPActivationABP1hypothesisIAAATP+H+SecondRoughERGolgi bodymessengersNUCLEUSATP6+H+Proteinprocessing鞋PromoterH+-ATPasegeneATPH+mRNASynthesishypothesisH+-ATPase?invesiclemembranePlasmaH+ActivationCELL WALLmembraneExpansinFIGURE19.25Current models for IAA-induced Ht extrusion. In many plants,bothof these mechanisms may operate.Regardless of how Htpumping is increased,acid-induced wall loosening is thoughtto be mediated by expansins.Figure 10-6
Figure 10-6
IAAconcentration(mg/ml)0.030.181.083.00.00.0050.0e0.21.0FiGuRE21.13Theregulationof growthand organformation incultured tobacco callusatdifferentconcentrations of auixin andkinetin.Atlow auxinand high kinetin concentrations (lower left)buds developed.Athigh auxin and low kinetin concentrations(upperright)rootsdevelopedAtintermediateorhighconcentrations ofbothhormones (middle and lowerright)undifferentiatedcallusdeveloped.(CourtesyofDonaldArmstrong.)Figure 10-7
Figure 10-7
1大抱子形成3、胚乳，糊粉层（单子叶植物）2柄退化毛状体发育4、aH7、叶衰老9、过敏反应（抗病）8通气组织形成5、管状分子形成6.根冠aFig.10-8
Fig.10-8