1_GBIntroductionPart1.ppt

LectureOutlinesbyGregoryAhearn UniversityofNorthFlorida Chapter1 AnIntroductionToLifeOnEarth Goalsoflearning Anavigationallearningofwhatislife andwhatislifescience Trynottothinkthecontentsaretoosimple Developacohesiveknowledgeofthecharacteristicsoflivingthings whichwouldenablepeopletodiscovernewcodes logicsoflife Fosteringanattitudeofinquiryandappreciationoftheknowledgegainedthroughscience Tobeinspiredaboutlifescience studentsmustappreciatethatlifescienceisaboutourownbody howitworks andmaintainshealth etc Howtostudy Theflowwillbebasedontheassignedtextbook EmphasiswillbecoveredinlecturePowerPointslides Toperformwell studentsareadvisedtoreadtheentirechaptersandrevisethoroughlyovertheslides Chapter1 1 1Whatarethecharacteristicsoflivingthings 1 2Howdoscientistsstudylife 1 3Howdoscientistscategorizethediversityoflife DefininglifeThedictionarydefinitionoflifeis thequalitythatdistinguishesavitalandfunctioningbeingfromadeadbody Livingthingsaremorethanthesumoftheirparts livingorganismsarenotamerecollectionofinanimatematerials Thecomplexityandorderedinteractionsofpartsinlivingthingsgiverisetocertainproperties Whatislife Organismsarecomplex organized andcomposedofcellsOrganismsacquireandusematerialsandenergyOrganismsmaintainrelativelyconstantinternalconditionsthroughhomeostasisOrganismsperceiveandrespondtostimuliOrganismsgrowandreproduceOrganismscanevolve 1 1Whatarethecharacteristicsoflivingthings Organization Livingthingsarecomposedofcells continued Allcellscontain GenesthatprovideinformationtocontrolthelifeofthecellOrganelles whicharesmall specializedstructuresthatperformspecificfunctionsAplasmamembranethatenclosesthefluidcytoplasmandorganellesfromtheoutsideworld LivingthingsarecomposedofcellsLivingthingsarebothcomplexandorganized atoms molecules Organelles cells tissues organs systems organisms organizedcomplexity Useofmaterials Livingthingsacquirematerials continued Importantmaterials nutrients areacquiredfromair water soil orotherlivingthingsNutrientsareincorporatedintothebodiesoforganismsNutrientsarecontinuouslyrecycledamonglivingandnonlivingthings Acquisitionofenergy LivingthingsobtainenergyintwowaysPlantsandsomesingle celledorganismscapturesunlightinphotosynthesisOtherorganismsconsumeenergy richmoleculesinthebodiesofotherorganismsAllenergythatsustainslifecomesdirectlyorindirectlyfromthesun Organismsuseenergy 1 buildpartsofcells2 movearound work 3 generateheat4 maintainhomeostasis5 grow develop andreproduce LivingthingsacquirematerialsMaterialsandenergyarerequiredfortheorganismtomaintainorganization togrow andtoreproduce Organismsabsorbenergy TheFlowofEnergyandtheRecyclingofNutrients HomeostasisOrganismsmustmaintainrelativelyconstantinternalconditions orhomeostasisbodytemperature energylevelHomeostaticmechanismsinclude SweatinginhotweatherordousingoneselfwithcoolwaterMetabolizingmorefood baskinginthesun orturningupthethermostatincoldweatherWhenAMP ATPisincreased cellsincreasecatabolic 分解 processes fattyacidoxidation whiledecreasinganabolic 合成 rates suchasfatsynthesis Organismsmaintainhomeostasis 稳态 LivingthingsrespondtostimuliOrganismssenseandrespondtointernalandexternalenvironmentalstimuli 刺激物 信号 Sensoryorgansinanimalscandetectandrespondtoexternalstimulilikelight sound chemicals etc Internalstimuliinanimalsareperceivedbystretch 伸展 temperature pain andchemicalreceptorsPlantsandbacteriarespondtostimuliaswell e g plantsgrowtowardthelight andbacteriamovetowardavailablenutrientsinamedium Organismsrespondtostimuli Sunlight chemicals hormones heat touch Growth LivingthingsgrowEveryorganismbecomeslargerovertimePlants birds andmammalsgrowbyproducingmorecellstoincreasetheirmassBacteriagrowbyenlargingtheircells theyalsodividetomakemoreindividualsGrowthinvolvestheconversionofacquiredmaterialstomoleculesoftheorganism sbody LivingthingsreproducethemselvesOrganismsgiverisetooffspringofthesametypeTheparent sgeneticmaterial DNA ispassedontotheoffspring creatingcontinuityoflife Reproduction Organismsreproduce Asexualreproduction Sexualreproduction Evolution LivingthingshavethecapacitytoevolveThegeneticcompositionofawholespecieschangesovermanygenerationsMutationsandvariableoffspringallowaspeciestoevolve Organismscanevolve protists 原生生物 Notetotheevolutiontreeshownabove Itisstillundercontroversyastowhyarchaeaareclosertoeukarya butnottobacteria ThedetailswillbediscussedbyProfessorWANGYiquan Itisrelativelyclearthatalthoughbothareprokaryotes bacteriaandarchaeaaredifferent forinstance peptidoglycans 聚糖肽 areinbacteria butnotinarchaea Evolutionistheprocessbywhichmodernorganismsdescended withmodifications frompreexistingformsoflifeDarwinandWallaceformulatedthebasisofourmodernunderstandingofevolutionEvolutionarisesasaconsequenceofthreenaturalprocesses seethefollowingslide ThreenaturalprocessesunderlieevolutionGeneticvariationamongmembersofapopulationduetodifferencesintheirDNAInheritanceofthosevariationsbyoffspringofparentscarryingthevariationNaturalselectionofindividualswhosesurvivalandenhancedreproductionareduetothefavorablevariationstheycarry GeneticvariabilityGeneticvariationarisesfromsegmentsofDNAChangesingenes mutations altertheinformationalcontentMutationsarisefromanumberofsourcesMutationscanoccurfromirradiationMutationsoccasionallyarisefromcopyingmistakesinDNAduringcellularreproductionMutationscanoccurspontaneously Geneticvariability continued EffectsofmutationNoeffect harmless LossoffunctionDeathoftheorganismDominantnegativeeffectGain of functionMutationsoccurringovermillionsofyearsandpassedthroughmanygenerationscausemembersofaspeciestobeslightlydifferent NaturalselectionOrganismsthatbestmeetenvironmentalchallengesleavethemostoffspringNaturalselectionpreservesgenesthathelporganismsflourishAdaptationsarestructures physiologicalprocess orbehaviorsthataidinsurvivalandreproductionAdaptationsthataregoodforoneenvironmentmaybepoorinanotherSpeciesthatcannotadapttoenvironmentalchangegoextinct forexample thedinosaurs Naturalselection continued Themanydifferenthabitats environments inanareacoupledwithevolutionaryadaptiveprocessesproducespeciesvariety orbiodiversityHumansareresponsibleforacceleratingtherateofenvironmentalchange andtherefore therateofextinctionofspecies 1 2HowDoScientistsStudyLife LifecanbestudiedatdifferentlevelsAtom molecule cellTissue organ organsystemMulticellularorganism population species estimatedat8 7million Community ecosystem biosphere HowDoScientistsStudyLife ScientificprinciplesunderlieallscientificinquiryNaturalcausalityistheprinciplethatalleventscanbetracedtonaturalcausesNaturallawsapplytoeverytimeandplaceScientificinquiryisbasedontheassumptionthatpeopleperceivenaturaleventsinsimilarways HowDoScientistsStudyLife ThescientificmethodisthebasisforscientificinquiryObservationQuestionHypothesisPredictionExperimentorObservationConclusion TheScientificMethod HowDoScientistsStudyLife ThescientificmethodScientificinquiryisarigorous 严格的 严密的 methodformakingobservationsThescientificmethodforinquiryfollowssixsteps HowDoScientistsStudyLife Thescientificmethod continued 1 Observationofaspecificphenomenon2 Theobservation inturn leadstoaquestionThequestionleadstoformulationofahypothesis basedonpreviousobservations thatisofferedasananswertothequestionThehypothesisleadstoaprediction typicallyexpressedin if then languageThepredictionistestedbycarefullycontrolledmanipulations 操作 calledexperimentsTheexperimentsproduceresultsthateithersupportorrefutethehypothesis allowingthedevelopmentofaconclusion HowDoScientistsStudyLife Thescientificmethod continued ControlsareincorporatedintoexperimentsControlskeepuntestedvariablesconstantThescientificmethodisillustratedbyexperimentsbyFrancescoRediandMalteAndersson TheExperimentsofFrancescoRedi Redipublishedhisseriesofexperimentsonthegenerationofinsectsin1668 whichisregardedashismasterpieceandamilestoneinthehistoryofmodernscience Thebookisoneofthefirststepsinrefuting spontaneousgeneration 自发生成 atheoryalsoknownasAristotelianabiogenesis Atthetime prevailingwisdomwasthatmaggots 蛆 arosespontaneouslyfromrottingmeat TheRediExperiment Conclusion Theexperimentsupportsthehypothesisthatfliesarethesourceofmaggots andthatspontaneousgenerationofmaggotsdoesnotoccur HowDoScientistsStudyLife ApplicationofthescientificmethodtoeverydayproblemsAssumeyouarelateforanappointmentandhurriedlytrytostartyourcarObservation Thecarwon tstartQuestion Whywon tthecarstart Hypothesis ThebatteryisdeadPrediction IFthehypothesisiscorrect THENthecarwillstartifthebatteryisreplacedExperiment Thebatteryisreplacedandthecarstarts HowDoScientistsStudyLife LimitationsofthescientificmethodOnecanneverbesurealluntestedvariablesarecontrolledConclusionsbasedontheexperimentaldatamustremaintentative HowDoScientistsStudyLife Scienceisahumanendeavor 努力 Humanpersonalitytraitsarepartof realscience Scientists likeotherpeople maybedrivenbypride ambition orfearScientistssometimesmakemistakesAccidents luckyguesses intellectualpowers andcontroversieswithotherscontributestronglytoscientificadvances HowDoScientistsStudyLife Scienceisahumanendeavor continued Inthe1920s bacteriologistAlexanderFleminggrewbacteriainculturesOneofthebacterialculturesbecamecontaminatedwithamoldFlemingnearlydestroyedtheculturewhenhenoticedthemold Penicillium inhibitedbacterialgrowthinthecultureFleminghypothesizedthatthemoldproducedanantibacterialsubstanceFurthertestsusingbrothfrompurePenicilliumculturesleadtothediscoveryofthefirstantibiotic penicillin PenicillinKillsBacteria HowDoScientistsStudyLife Scienceisahumanendeavor continued Flemingcontinuedbeyondalucky accident withfurtherscientificinvestigationtoagreatdiscovery Chancefavorsthepreparedmind LouisPasteur HowDoScientistsStudyLife ScientifictheoriesAscientifictheoryisageneralexplanationforimportantnaturalphenomenaItisextensivelyandreproduciblytestedItismorelikeaprincipleornaturallaw e g theatomic gravitational andcelltheories Ifcompelling 引人注目的 evidencearises atheorymaybemodified HowDoScientistsStudyLife Scientifictheories continued Newscientificevidencemaypromptradical 根本的 彻底的 revisionofexistingtheoryForexample thediscoveryofprions 朊ruan病毒 AscientifictheorydiffersindefinitionfromthatofeverydayusageManypeopleusethewordtheorytomeanhypothesis oran educatedguess Intheory HowDoScientistsStudyLife ThediscoveryofprionsBefore1980 allknowninfectiousdiseasescontainedDNAorRNAIn1982 StanleyPrusinershowedthattheinfectioussheepdiseasescrapieiscausedbyaprotein a proteininfectiousparticle orprion HowDoScientistsStudyLife Thediscoveryofprions continued Prionshavesincebeenshowntocause madcowdisease anddiseasesinhumansThewillingnessofscientiststoreviseacceptedbeliefinlightofnewdatawascriticaltounderstandingandexpandingthestudyofprions HowDoScientistsStudyLife ScienceisbasedonreasoningInductivereasoning 归纳 isusedinthedevelopmentofscientifictheoriesAgeneralizationiscreatedfrommanyobservationsForexample thecelltheory thatalllivingthingsaremadeofoneormorecells arisesfrommanyobservationsthatallindicateacellularbasisforlife HowDoScientistsStudyLife Scienceisbasedonreasoning continued Deductivereasoning 演绎 istheprocessofgeneratinghypothesesbasedonawell supportedgeneralization suchasatheory Forexample basedonthecelltheory anynewlydiscoveredorganismwouldbeexpectedtobecomposedofcells 1 3ClassificationofSpecies Howdoscientistscategorizethediversityoflife Scientistsgenerallycategorizeorganismsintothreemajorgroups ordomains BacteriaArchaea 古細菌 古生菌或太古生物 构成生物分类的一个域 Eukarya Thedomainsandkingdomsoflife Threedomainsand6kingdoms ThedomainEukaryacontainsfoursubdivisions orkingdomsFungiPlantaeAnimaliaThe protists Twocelltyp