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ID:45262066
大小:9.41 MB
页数:116页
时间:2019-11-11
《9.Cell-Cycle+and+Cell+Division(2007)》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、Chapter9Cell-CycleandCellDivisionOverviewofthecellcycleRegulationofthecellcycleCelldivisionCell-CycleandCellDivision根据增殖状况,细胞分类三类·连续分裂细胞(cyclingcell)·休眠细胞(Go细胞)·终末分化细胞G0期细胞和终末分化细胞的界限有时难以划分,有的细胞过去认为属于终末分化细胞,目前可能被认为是G0期细胞。OverviewofthecellcyclecellgrowthDNAreplicationdi
2、stributionoftheduplicatedchromosomescelldivisionThecellcyclecanbedividedintotwomajorphasesbasedoncellularactivities,interphaseandMphase.Mphaseincludesmitosisandcytokinesis.InterphaseistheintervalbetweendivisionsisdividedintoG1,SandG2phases.sothecellcycleincludesfourph
3、ases:G1,S,G2andMphases.Analysisofalargevarietyofcellshasrevealedgreatvariabilityinthelengthsoftheircellcycle.Thefourstagesofcellcycle,G1isthemostvariable.WhilethetotaltimeofS,G2andMphasesisrelativelyfixed.Itisthecell-cyclecontrolsystemthatensurescorrectprogressionthro
4、ughthecellcyclebyregulatingthecell-cyclemachinery.Theprogressionofcellsthroughthedivisioncycleisregulatedbyextracellularsignalsfromtheenvironmentandinternalsignals.CellcyclecontrolCellCycleCheckpointsCyclinsProgressionregulatoryofcellcycleRegulationofThecellcycleAmajo
5、rcellcycleregulatorypointinmanytypesofcellsoccurslateinG1andcontrolsprogressionfromG1toS.Inadditiontoservingasadecisionpointformonitoringextracellularsignals,STARTisthepointatwhichcellgrowthiscoordinatedwithDNAreplicationandcelldivision.Theproliferationofmostanimalcel
6、lsissimilarlyregulatedintheG1phaseofthecellcycle.Inparticular,adecisionpointinlateG1,calledtherestrictionpointinanimalcells.Theproliferationofthesecellsistriggeredbyplatelet-derivedgrowthfactor,whichisreleasedfrombloodplateletsduringclottingandsignalstheproliferationo
7、ffibroblasts(纤维原细胞)inthevicinityoftheinjuredtissue.CellCycleCheckpointsInmostcells,thecoordinationbetweendifferentphasesofthecellcycleisdependentonasystemofcheckpointsandfeedbackcontrolsthatprevententryintothenextphaseofthecellcycleuntiltheeventsoftheprecedingphasehav
8、ebeencompleted.Atleast,therearethreemajorcheckpointsexistwithinthecellcycle,G1/Scheckpoint,G2/McheckpointandMcheckpoint.TheG
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