台湾清华大学生命科学第十三讲焦传金教授省公共课一等奖全国赛课获奖课件.pptx

Copyright Pearson Education,Inc.,publishing as Pearson Benjamin CummingsPowerPoint Lecture Presentations forBiologyEighth EditionNeil Campbell and Jane ReeceLectures by Chris Romero,updated by Erin Barley with contributions from Joan SharpChapter 12The Cell Cycle第1页Overview:The Key Roles of Cell Division The ability of organisms to reproduce bestdistinguishes living things from nonliving matter The continuity of life is based on thereproduction of cells,or cell divisionCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第2页 In unicellular organisms,division of one cellreproduces the entire organism Multicellular organisms depend on cell divisionfor:Development from a fertilized cell Growth Repair Cell division is an integral part of the cell cycle,the life of a cell from formation to its owndivisionCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第3页Fig.12-2100 m200 m20 m(a)Reproduction(b)Growth anddevelopment(c)Tissue renewalThe functions of cell division第4页Concept 12.1:Cell division results in geneticallyidentical daughter cells Most cell division results in daughter cells withidentical genetic information,DNA A special type of division produces nonidenticaldaughter cells(gametes,or sperm and eggcells)Copyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第5页Cellular Organization of the Genetic Material All the DNA in a cell constitutes the cellsgenome A genome can consist of a single DNAmolecule(common in prokaryotic cells)or anumber of DNA molecules(common ineukaryotic cells)DNA molecules in a cell are packaged intochromosomesCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第6页Fig.12-3Eukaryotic chromosomes20 m第7页 Every eukaryotic species has a characteristicnumber of chromosomes in each cell nucleus Somatic cells(nonreproductive cells)havetwo sets of chromosomes Gametes(reproductive cells:sperm and eggs)have half as many chromosomes as somaticcells Eukaryotic chromosomes consist of chromatin,a complex of DNA and protein that condensesduring cell divisionCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第8页Distribution of Chromosomes During EukaryoticCell Division In preparation for cell division,DNA isreplicated and the chromosomes condense Each duplicated chromosome has two sisterchromatids,which separate during celldivision The centromere is the narrow“waist”of theduplicated chromosome,where the twochromatids are most closely attachedCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第9页Fig.12-40.5 mChromosomesChromosomeduplicationChromo-some armDNA molecules(including DNAsynthesis)CentromereSisterchromatidsSeparation ofsister chromatidsCentromereSister chromatids第10页 Eukaryotic cell division consists of:Mitosis,the division of the nucleus Cytokinesis,the division of the cytoplasm Gametes are produced by a variation of celldivision called meiosis Meiosis yields nonidentical daughter cells thathave only one set of chromosomes,half asmany as the parent cellCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第11页Concept 12.2:The mitotic phase alternates withinterphase in the cell cycle In 1882,the German anatomist WaltherFlemming developed dyes to observechromosomes during mitosis and cytokinesis The cell cycle consists of Mitotic(M)phase(mitosis and cytokinesis)Interphase(cell growth and copying ofchromosomes in preparation for cell division)Copyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第12页 Interphase(about 90%of the cell cycle)can bedivided into subphases:G1 phase(“first gap”)S phase(“synthesis”)G2 phase(“second gap”)The cell grows during all three phases,butchromosomes are duplicated only during the SphaseCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第13页Fig.12-5G1S(DNA synthesis)G2The cell cycle第14页 Mitosis is conventionally divided into fivephases:Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis is well underway by late telophaseBioFlix:MitosisCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第15页2 of InterphaseGcentriole (duplicated)Prophase CentromerePrometaphaseFig.12-6aPrometaphaseFragments Nonkinetochoreof nuclear microtubulesenvelopeProphaseEarly mitotic AsterspindleG2 of InterphaseCentrosomes Chromatin(withpairs)Nucleolus NuclearPlasmaenvelope membraneChromosome,consistingof two sister chromatidsKinetochoreKinetochoremicrotubule第16页Telophase and CytokinesisFig.12-6cMetaphaseAnaphase AnaphaseTelophase and CytokinesisCleavagefurrowNucleolusformingMetaphaseplateCentrosome atone spindle poleSpindleDaughterchromosomesNuclearenvelopeforming第17页The Mitotic Spindle:A Closer Look The mitotic spindle is an apparatus ofmicrotubules that controls chromosomemovement during mitosis During prophase,assembly of spindlemicrotubules begins in the centrosome,themicrotubule organizing center The centrosome replicates,forming twocentrosomes that migrate to opposite ends ofthe cell,as spindle microtubules grow out fromthemCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第18页 An aster(a radial array of short microtubules)extends from each centrosome The spindle includes the centrosomes,thespindle microtubules,and the astersCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第19页 During prometaphase,some spindlemicrotubules attach to the kinetochores ofchromosomes and begin to move thechromosomes At metaphase,the chromosomes are all linedup at the metaphase plate,the midway pointbetween the spindles two polesCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第20页Fig.12-7AsterCentrosomeSisterchromatidsMetaphaseplateKineto-choresKinetochoremicrotubulesOverlappingnonkinetochoremicrotubulesMicrotubulesCentrosomeChromosomes1 mThe mitotic spindle at metaphase0.5 m第21页 In anaphase,sister chromatids separate andmove along the kinetochore microtubulestoward opposite ends of the cell The microtubules shorten by depolymerizing attheir kinetochore endsCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第22页Fig.12-8EXPERIMENTKinetochoreSpindlepoleMarkRESULTSCONCLUSIONChromosomemovementKinetochoreMotorMicrotubule proteinChromosomeTubulinsubunits第23页 Nonkinetochore microtubules from oppositepoles overlap and push against each other,elongating the cell In telophase,genetically identical daughternuclei form at opposite ends of the cellCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第24页Cytokinesis:A Closer Look In animal cells,cytokinesis occurs by a processknown as cleavage,forming a cleavagefurrow In plant cells,a cell plate forms duringcytokinesisCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第25页Fig.12-9Cleavage furrow100 mContractile ring ofmicrofilamentsDaughter cells(a)Cleavage of an animal cell(SEM)(b)Cell plate formation in a plant cell(TEM)Vesiclesformingcell plateWall ofparent cellCell plateDaughter cells1 mNew cell wallCytokinesis in animal and plant cells第26页Fig.12-10Chromatincondensing1 Prophase2 Prometaphase3 Metaphase5 Telophase4 AnaphaseNucleusNucleolusChromosomesCell plate10 mMitosis in a plant cell第27页Binary Fission Prokaryotes(bacteria and archaea)reproduceby a type of cell division called binary fission In binary fission,the chromosome replicates(beginning at the origin of replication),andthe two daughter chromosomes actively moveapartCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第28页Fig.12-11-4Cell wallOrigin ofreplicationE.coli cellTwo copiesof originOriginPlasmamembraneBacterialchromosomeOrigin第29页The Evolution of Mitosis Since prokaryotes evolved before eukaryotes,mitosis probably evolved from binary fission Certain protists exhibit types of cell division thatseem intermediate between binary fission andmitosisCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第30页Fig.12-12Bacterialchromosome(a)BacteriaChromosomesMicrotubulesIntact nuclearenvelope(b)DinoflagellatesKinetochoremicrotubuleIntact nuclearenvelope(c)Diatoms and yeastsKinetochoremicrotubuleFragments ofnuclear envelope(d)Most eukaryotes第31页Concept 12.3:The eukaryotic cell cycle is regulatedby a molecular control system The frequency of cell division varies with thetype of cell These cell cycle differences result fromregulation at the molecular levelCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第32页Evidence for Cytoplasmic Signals The cell cycle appears to be driven by specificchemical signals present in the cytoplasm Some evidence for this hypothesis comes fromexperiments in which cultured mammalian cellsat different phases of the cell cycle were fusedto form a single cell with two nucleiCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第33页Fig.12-13Experiment 1Experiment 2EXPERIMENTRESULTSSG1MG1MMSSWhen a cell in theS phase was fusedwith a cell in G1,the G1nucleus immediatelyentered the SphaseDNA wassynthesized.When a cell in theM phase was fused witha cell in G1,the G1nucleus immediatelybegan mitosisaspindle formed andchromatin condensed,even though thechromosome had notbeen duplicated.Molecular signals in the cytoplasmregulate the cell cycle第34页The Cell Cycle Control System The sequential events of the cell cycle aredirected by a distinct cell cycle controlsystem,which is similar to a clock The cell cycle control system is regulated byboth internal and external controls The clock has specific checkpoints where thecell cycle stops until a go-ahead signal isreceivedCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第35页Fig.12-14SG1MControlsystemG2G1 checkpointM checkpointG2 checkpoint第36页 For many cells,the G1 checkpoint seems to bethe most important one If a cell receives a go-ahead signal at the G1checkpoint,it will usually complete the S,G2,and M phases and divide If the cell does not receive the go-ahead signal,it will exit the cycle,switching into a nondividingstate called the G0 phaseCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第37页Fig.12-15G0G1 checkpointG1(a)Cell receives a go-aheadsignalG1(b)Cell does not receive ago-ahead signal第38页The Cell Cycle Clock:Cyclins andCyclin-Dependent Kinases Two types of regulatory proteins are involved incell cycle control:cyclins and cyclin-dependent kinases(Cdks)The activity of cyclins and Cdks fluctuatesduring the cell cycle MPF(maturation-promoting factor)is a cyclin-Cdk complex that triggers a cells passage pastthe G2 checkpoint into the M phaseCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第39页Fig.12-16Time(min)3002004001002105305004203100RESULTS第40页Cyclin accumulationFig.12-17MG1SG2MG1SG2MG1MPF activityCyclinconcentrationTime(a)Fluctuation of MPF activity and cyclin concentration duringthe cell cycleCdkDegradedG2checkpointcyclinCyclin isdegradedCdkCyclinMPF(b)Molecular mechanisms that help regulate the cell cycle第41页Stop and Go Signs:Internal and External Signals atthe Checkpoints An example of an internal signal is thatkinetochores not attached to spindlemicrotubules send a molecular signal thatdelays anaphase Some external signals are growth factors,proteins released by certain cells that stimulateother cells to divide For example,platelet-derived growth factor(PDGF)stimulates the division of humanfibroblast cells in cultureCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第42页Fig.12-18PetriplateScalpelsCultured fibroblastsWithout PDGFcells fail to divideWith PDGFcells prolifer-ate10 mThe effect of a growth factor oncell division第43页 Another example of external signals is density-dependent inhibition,in which crowded cellsstop dividing Most animal cells also exhibit anchoragedependence,in which they must be attachedto a substratum in order to divideCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第44页Fig.12-19(a)Normal mammalian cells(b)Cancer cells25 m25 mDensity-dependent inhibition andanchorage dependence of cell divisionAnchorage dependenceDensity-dependent inhibitionDensity-dependent inhibition第45页 Cancer cells exhibit neither density-dependentinhibition nor anchorage dependenceCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第46页Loss of Cell Cycle Controls in Cancer Cells Cancer cells do not respond normally to thebodys control mechanisms Cancer cells may not need growth factors togrow and divide:They may make their own growth factor They may convey a growth factors signalwithout the presence of the growth factor They may have an abnormal cell cycle controlsystemCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第47页 A normal cell is converted to a cancerous cellby a process called transformation Cancer cells form tumors,masses of abnormalcells within otherwise normal tissue If abnormal cells remain at the original site,thelump is called a benign tumor Malignant tumors invade surrounding tissuesand can metastasize,exporting cancer cells toother parts of the body,where they may formsecondary tumorsCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第48页Fig.12-20TumorGlandulartissueBloodvesselCancercellMetastatictumortumor in anotherpart of the body.1 A tumor growsfrom a singlecancer cell.2 Cancer cellsinvade neigh-boring tissue.3 Cancer cells spreadto other parts ofthe body.4 Cancer cells maysurvive andestablish a newThe growth and metastasis of amalignant breast tumorLymphvessel第49页You should now be able to:1.Describe the structural organization of theprokaryotic genome and the eukaryoticgenome2.List the phases of the cell cycle;describe thesequence of events during each phase3.List the phases of mitosis and describe theevents characteristic of each phase4.Draw or describe the mitotic spindle,includingcentrosomes,kinetochore microtubules,nonkinetochore microtubules,and astersCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第50页5.Compare cytokinesis in animals and plants6.Describe the process of binary fission inbacteria and explain how eukaryotic mitosismay have evolved from binary fission7.Explain how the abnormal cell division ofcancerous cells escapes normal cell cyclecontrols8.Distinguish between benign,malignant,andmetastatic tumorsCopyright Pearson Education,Inc.,publishing as Pearson Benjamin Cummings第51页