Cell structure and Functions

CellStructureandFunctionCells•Smallestlivingunit•MostaremicroscopicDiscoveryofCells•RobertHooke(mid-1600s)–Observedsliverofcork–Saw“rowofemptyboxes”–CoinedthetermcellCelltheory•(1839)TheodorSchwann&MatthiasSchleiden“alllivingthingsaremadeofcells”•(50yrs.later)RudolfVirchow“allcellscomefromcells”PrinciplesofCellTheory•Alllivingthingsaremadeofcells•Smallestlivingunitofstructureandfunctionofallorganismsisthecell•Allcellsarisefrompreexistingcells(thisprinciplediscardedtheideaofspontaneousgeneration)CellSizeCellsHaveLargeSurfaceArea-to-VolumeRatioCharacteristicsofAllCells•Asurroundingmembrane•Protoplasm–cellcontentsinthickfluid•Organelles–structuresforcellfunction•ControlcenterwithDNACellTypes•Prokaryotic•EukaryoticProkaryoticCells•Firstcelltypeonearth•CelltypeofBacteriaandArchaeaProkaryoticCells•Nomembraneboundnucleus•Nucleoid=regionofDNAconcentration•OrganellesnotboundbymembranesEukaryoticCells•Nucleusboundbymembrane•Includefungi,protists,plant,andanimalcells•PossessmanyorganellesProtozoanRepresentativeAnimalCellRepresentativePlantCellOrganelles•Cellularmachinery•Twogeneralkinds–Derivedfrommembranes–Bacteria-likeorganellesPlasmaMembrane•Containscellcontents•Doublelayerofphospholipids&proteinsPhospholipids•Polar–Hydrophylichead–Hydrophobictail•InteractswithwaterMovementAcrossthePlasmaMembrane•Afewmoleculesmovefreely–Water,Carbondioxide,Ammonia,Oxygen•Carrierproteinstransportsomemolecules–Proteinsembeddedinlipidbilayer–Fluidmosaicmodel–describesfluidnatureofalipidbilayerwithproteinsMembraneProteins1.Channelsortransporters–Movemoleculesinonedirection2.Receptors–RecognizecertainchemicalsMembraneProteins3.Glycoproteins–Identifycelltype4.Enzymes–CatalyzeproductionofsubstancesCellWalls•Foundinplants,fungi,&manyprotists•SurroundsplasmamembraneCellWallDifferences•Plants–mostlycellulose•Fungi–containchitinCytoplasm•Viscousfluidcontainingorganelles•componentsofcytoplasm–Interconnectedfilaments&fibers–Fluid=cytosol–Organelles(notnucleus)–storagesubstancesCytoskeleton•Filaments&fibers•Madeof3fibertypes–Microfilaments–Microtubules–Intermediatefilaments•3functions:–mechanicalsupport–anchororganelles–helpmovesubstancesA=actin,IF=intermediatefilament,MT=microtubuleCilia&Flagella•Providemotility•Cilia–Short–Usedtomovesubstancesoutsidehumancells•Flagella–Whip-likeextensions–Foundonspermcells•BasalbodieslikecentriolesCilia&FlagellaStructure•Bundlesofmicrotubules•WithplasmamembraneCentrioles•Pairsofmicrotubularstructures•PlayaroleincelldivisionMembranousOrganelles•Functionalcomponentswithincytoplasm•BoundbymembranesNucleus•Controlcenterofcell•Doublemembrane•Contains–Chromosomes–NucleolusNuclearEnvelope•Separatesnucleusfromrestofcell•Doublemembrane•HasporesDNA•Hereditarymaterial•Chromosomes–DNA–Protiens–Formforcelldivision•ChromatinNucleolus•Mostcellshave2ormore•DirectssynthesisofRNA•FormsribosomesEndoplasmicReticulum•Helpsmovesubstanceswithincells•Networkofinterconnectedmembranes•Twotypes–Roughendoplasmicreticulum–SmoothendoplasmicreticulumRoughEndoplasmicReticulum•Ribosomesattachedtosurface–Manufactureprotiens–NotallribosomesattachedtoroughER•MaymodifyproteinsfromribosomesSmoothEndoplasmicReticulum•Noattachedribosomes•Hasenzymesthathelpbuildmolecules–Carbohydrates–LipidsGolgiApparatus•Involvedinsynthesisofplantcellwall•Packaging&shippingstationofcellGolgiApparatusFunction1.Moleculescomeinvesicles2.VesiclesfusewithGolgimembrane3.MoleculesmaybemodifiedbyGolgiGolgiApparatusFunction(Continued)4.Moleculespinched-offinseparatevesicle5.VesicleleavesGolgiapparatus6.VesiclesmaycombinewithplasmamembranetosecretecontentsLysosomes•Containdigestiveenzymes•Functions–Aidincellrenewal–Breakdownoldcellparts–DigestsinvadersVacuoles•Membraneboundstoragesacs•Morecommoninplantsthananimals•Contents–Water–Food–wastesBacteria-LikeOrganelles•Release&storeenergy•Types–Mitochondria(releaseenergy)–Chloroplasts(storeenergy)Mitochondria•HavetheirownDNA•BoundbydoublemembraneMitochondria•Breakdownfuelmolecules(cellularrespiration)–Glucose–Fattyacids•Releaseenergy–ATPChloroplasts•Derivedformphotosyntheticbacteria•SolarenergycapturingorganellePhotosynthesis•Takesplaceinthechloroplast•Makescellularfood–glucoseReviewofEukaryoticCellsReviewofEukaryoticCellsMoleculeMovement&Cells•PassiveTransport•ActiveTransport•Endocytosis(phagocytosis&pinocytosis)•ExocytosisPassiveTransport•Noenergyrequired•Moveduetogradient–differencesinconcentration,pressure,charge•Movetoequalizegradient–HighmovestowardlowTypesofPassiveTransport1.Diffusion2.Osmosis3.FacilitateddiffusionDiffusion•MoleculesmovetoequalizeconcentrationOsmosis•Specialformofdiffusion•Fluidflowsfromlowersoluteconcentration•Ofteninvolvesmovementofwater–Intocell–OutofcellSolutionDifferences&Cells•solvent+solute=solution•Hypotonic–Solutesincellmorethanoutside–Outsidesolventwillflowintocell•Isotonic–Solutesequalinside&outofcell•Hypertonic–Solutesgreateroutsidecell–FluidwillflowoutofcellFacilitatedDiffusion•Differentiallypermeablemembrane•Channels(arespecific)helpmoleculeorionsenterorleavethecell•Channelsusuallyaretransportp