分子细胞生物学 1

分子细胞生物学MolecularCELLBIOLOGY,Chapter1,Introductiontothecell,LearningObjectives,1.AboutCellBiology2.Lookbrieflyatthehistoryofcelltheory;3.Considerthebasicpropertiesofcells;4.Comparesomecharacteristicsoftwodifferentclassesofcells:prokaryotesandeukaryotes;5.Comprehendaspeciallife:viruses,1.About“CellBiology”,What?Forwhy?Howtostudy?,TheNIHofUSA(1988):“Whatispopularinresearchtoday？”3kindsofdiseases：cancercardiovasculardiseasesinfectiousdiseases：AIDS，hepatitis5researchfields：cellcyclecontrol；cellapoptosis；cellularsenescence；signaltransduction；DNAdamageandrepair.,Whatweknow/Howweknow.,ISI,USA(1997):SCI（ScienceCitationIndex）Papers:Threetopsofresearchfields:No1:Signaltransduction；No2:Cellapoptosis；No3:Genomeandpost-genomicanalysis。,2.TheCellTheory:ABriefHistory,In1665,RobertHookesawanetworkoftinyboxlikecompartmentsthatremindedhimofahoneycomb.Hecalledtheselittlecompartments“cellulae”,aLatintermmeaninglittleroom.Itisfromthiswordwegetourpresent-dayterm,cell.,ThemicroscopeusedbyRobertHookeandthehoneycomb-likenetworkof“cell”hedrawedin1665,Thediscoveryofcellsfollowedfromtheinventionofthemicroscope,Celltheoryhasthreebasictenets:,1.Allorganismsarecomposedofoneormorecells.,2.Thecellisbasicunitofstructureandfunctionforallorganisms.,3.Allcellsariseonlyfrompreexistingcellsbydivision.,3.Whyarecellsthebasicunitsoflife?,A.Thecellisthestructuralunitoflife,Allorganismsismakeupofcells.,B.Thecellisthefunctionalunitoforganisms.Allmetabolicactivityisbasedoncells.,C.Thecellisthefoundationofreproduce,andthebridgeofinheritance.,D.Thecellisthegrowinganddevelopingbasisoflife,Humanfetaldevelopment.(a)At5weeks,limbbuds,eyes,theheart,theliverandrudimentsofallotherorganshavestartedtodevelopintheembryo,whichisonlyabout1cmlong.(b)Growthanddevelopmentoftheoffspring,nowcalledafetus,continueduringthesecondtrimester.Thisfetusis14weeksoldandabout6cmlong.(c)Thefetusinthisphotographis20weeksold.Nowthefetusgrowstoabout30cminlength.,E.Cell(nucleus)istotipotent,whichcancreateaneworganismofthesametype,Asageneralrule,thecellsofamulticellularorganismallcontainthesamesetofgenes.Foranimals,thefirstevidencethatevenhighlyspecializedcellcarryafullcomplementofgeneswasverifiedbytheexperimentoftadpolenucleitransplantingintounfertilizedeggthathadbeendeprivedofitsownnucleus.Somecandevelopswimmingtadpoles.Thisisanimalcloning.Anespeciallydramaticexampleofanimalcloningwasreportedin1997.Dollythefirstanimaleverclonedfromacellderivedfromanadult.,Dollyandherdaughter,TheprocessofcloningDolly,Isthereanypracticalvaluetosuchtechnology?,4.Basicpropertiesofcells,Cellsarehighlycomplexandorganized,capableofself-regulation;Cellsacquireandutilizeenergy.B.Allcellssharesimilarstructure,compositionandmetabolicfeatures:Plasmamembrane,DNA/RNA,andRibosome.,C.Cellscancapableofproducingmoreofthemselves,evengrowandreproduceincultureforextendedperiods.,HeLacellsareculturedtumorcellsisolatedfromacancerpatientnamedHenriettaLacksin1951.Itisthefirsthumancelltobekeptincultureforlongperiodsoftimeandisstillusedtoday.JohnsHopkinsunivesity,in1951,D.Cellsareabletorespondtostimuliviasurfacereceptorsthatsensechangesinthechemicalenvironment.,Cellswithinplantoranimalrespondtostimulilessobviouslythansingle-celledprotist.Buttheyrespond.Theypossesreceptorsthatinteractwithsubstancesintheenvironmentinhighlyspecificways.Forexample,thereceptoronthecellsurfacecanrespondtohormonesandgrowthfactors.,5.TheSizeofCellsdiameterMeasuredinunitsofmicrometers:1um=10-6meternanometers:1nm=10-9meterc)Cellsizeislimited:nucleus/cytoplasmratio;surfacearea/volumeratio;substancescanefficientlytravelthroughthecytoplasmviadiffusion.,6.Twofundamentallydifferentclassesofcells:Prokaryotesandeukaryotes,A.Prokaryoticandeukaryoticcellsaredistinguishedbythesizeandthetypesofinternalstructures,ororganelles,especiallyifthereisnuclearenvelope.,Bacteriaareprokaryotes,theyarose3.5billionyearsago;Protists,fungi,plants,andanimalsareeukaryotes.Thefirsteukaryotesarose1.5billionyearsago.,B.Characteristicsthatdistinguishprokaryoticandeukaryoticcells,Complexity:Prokaryotesarerelativelysimple,eukaryotesaremorecomplexinstructureandfunction,pp.36Table2-2;2-3,(2)Geneticmaterial:AllCellsStoreTheirHereditaryInformationintheSameLinerChemicalCode(DNA),Packaging:Prokaryoteshaveanucleoidregionwhereasekukaryotehaveatrue,membrane-boundnucleus.b.Amount:Eukaryoteshaveseveralordersofmagnitudemoregeneticmaterialthanprokaryotes.c.Form:EukaryoteshavemanychromosomesthataremadeofbothDNAandproteinwhereasprokaryoteshaveasingleDNAchromosome,Packaging:Prokaryoteshaveanucleoidregionwhereasekukaryotehaveatrue,membrane-boundnucleus.(bacterinm:0.25-3.0mm,toencodebetweenseveralhundredandseveralthousandproteins,Thesimplestknowncellshavejustunder500genes).b.Amount:Eukaryoteshaveseveralordersofmagnitudemoregeneticmaterialthanprokaryotes.(yeast:4.6mmDNA,encodingabout6200proteins)c.Form:EukaryoteshavemanychromosomesthataremadeofbothDNAandproteinwhereasprokaryoteshaveasingle,“naked”DNAchromosome,(3)Cytoplasm:Eukaryoteshavemembrane-boundorganellesandcytoskeletalproteins;prokaryoteshaveneither.Bothhaveribosomes,althoughtheydifferinsize.(4)Cellularreproduction:Eukaryotesdividebymitosis;prokaryotesdividebysimplefission.(5)Locomotion:Eukaryotesusebothcytoplasmicmovement,andciliaandflagella;prokaryoteshaveflagella,buttheydifferinbothformandmechanismfromeukaryoticflagella.,C.ThreestructuralsystemsinEukaryotes:,Thedifferencebetweenprokaryoticandeukaryoticflagela,Flagellin,Humansperm,7.TypesofProkaryoticCells:TwoSubkingdoms,Treeoflifehasthreeprimarybranches.A.SubkingdomArchaeaSubkingdomBacteriaMostBacteriaandArchaeahave1000-4000genesThesmallestknowncells-theMycoplasma0.10.3m;smallestgenome:482genes,minimalessentialgene：256,8.Viruses,Virusdiversity,1.Virusesarepathogensfirstdescribedinthelate1800s.2.Viralstructure:a)Thegeneticmaterial:Single-ordouble-stradedDNAorRNA.b)obligatoryintracellularparasites.,3.Viralinfectiontypes:a)Lyticinfection;b)integratedinfection,4.Viralorigins:a)Viruseshadtoar