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高等生物化學:Life•簡介•生命體的基本組成:細胞(cell)•Prokaryotecell的組成及各別功能•Eukaryotecell的組成及各別功能•組成生命體的基本化學分子•生化領域的有關期刊Biochemistry-Chpater1:Life生物化學及其研究範疇什麼是生物化學?它和化學有什麼不同?Biochemistryisthestudyofthechemicalreactionsonthemolecularlevelthatoccurinlivingorganism.生物化學研究的目的?tointerpretthebiologicalfunctionsoflivingorganismsinthelanguageofchemistry.生物化學研究對象-生命體的定義為何?生命體具有下列特質:由環境中吸取營養，因應環境變化，成長及分化，繁衍。NormanHorowitz提出:•Alllivingthingsgrow,reproduce(replication)•Obtainenergyfromtheirsurroundings,buildnewmoleculesfrombasicorganicmolecules(catalysis)•Repairthemselves,andrespondtoexternalstimuli(mutability)國立中興大學生化所李天雄生命體的基本組成單位:細胞Alllivingthingsarecomposedofoneormorecellsandthatcellsaremoreorlessalikeandcarryoutsimilarfunctionstokeepthemselvesalive.MatthiasSchleiden&TheodorSchwann1839(truecelltheory)examinedacutsectionofcorkandgavethecavitieshesawthenamecell,meaninglittlerooms.RobertHooke1665usedmagnifyinglensestostudylivingworldinvisibletothenakedeye.AntonvanLeeuwenkoek1660Thedevelopmentofcelltheory早期已發展出生命體是由基本組成單位(細胞)的觀念而後按照細胞內部結構，區分為兩大類:eukaryotes(原核)和prokaryotes(真核),後者超過生物總體一半以上，能在任何地方(有氧或無氧，高低溫生存條件)存活，高複製繁衍速率特性，能有效運用短暫而有利生存條件狀況下繁衍，因此在衍化上勝過eukaryotes。Generalconceptsaboutcells1.Whatdocellslooklike?Thereisnogeneralcommonshape,cellcancomeinshapessuchascubes(cellsliningsweatducts),spheres(whitebloodcellsoftheimmunesystem),bismarckdoughnuts(redbloodcells),columns(cellsliningthegut),balloons(cellsliningtheurinarybladder),ellipsoidsorrods(somebacteria),andpancakes(cellsonthesurfaceoftheskin).Bacterialcellsareusuallyspherical,rod-shaped,comma-shaped,orcorkscrewshaped.2.Thecellsize?Cellsaremicroscopicinsize.Humanredbloodcellsareabout7.5micrometerswide,andareabout5-100timesaslargeasabacterialcell.Thediameterofatypicalsphericalbacterialcellisabout1µm,whilethehumanlivercell(hepatocyte)isroughly25µm.amicrometer,ormicron,微米(米達尺的最小單位-毫米再分成1000等分),isonemillionthofameterinlengthStreptococcusPneumoniae(bacteriumthatcauseslobarpneumonia.)(bacteriumthatcausestetanusinfections.)Mycobacteriumtuberculosis(bacteriumthatcausesTB)Proteusmirabilis(bacteriumthatcausesurinarytractandwoundsinfection.)EscherichiaColiHumannervecells,locatedinthespinalcordwheretheysendelectricalsignalstomusclecells.瞭解細胞的構造及細胞的分類Thebiochemicalprocessesmustbeviewedinthecontextofcellstructures.Thecellscanbedividedintotwobroadcategories,eukaryotesandprokaryotesdependingonwhetherornottheirDNAissurroundedbymembrane.Ineukaryotes,amembranesurroundstheDNAtoformaintracellularcompartmentcalledthenucleus.Prokaryotesdonothaveadefinednucleus.Intracellularmembrane-enclosedcompartments(calledorganelles)arethemajorcharacteristicintracellularstructureineukaryoteswhichensurebiologicalprocessestofunctionproperly.Prokaryotes生物界中最簡單，但是最有生命力的生物體。Procaryoticcellshavethreearchitecturalregions:1.appendages(proteinsattachedtothecellsurface)intheformofflagellaandpili.2.acellenvelopeconsistingofacapsule,cellwall(30~250Åthick)andplasmamembrane(~70Åthick).3.acytoplasmicregionthatcontainsthecellgenome(DNA)andribosomesandvarioussortsofinclusions.(cytoplasm)issurroundedbytheplasmamembrane,acellwallandacapsule.Allcellshaveamembrane,whichistheessentialanddefinitivecharacteristicofacell.Almostallprocaryoteshaveacellwalltopreventdamagetotheunderlyingprotoplast.Outsidethecellwall,foremostasasurfacestructure,maybeapolysaccharidecapsule.Mostprocaryotescontainsomesortofapolysaccharidelayeroutsideofthecellwallpolymer.Inageneralsense,thislayeriscalledacapsule.Atruecapsuleisadiscretedetectablelayerofpolysaccharidesdepositedoutsidethecellwall.Alessdiscretestructureormatrixwhichembedsthecellsisacalledaslimelayer.BacterialcapsulesoutlinedbyIndiainkviewedbylightmicroscopy.Thisisatruecapsule,adiscretelayerofpolysaccharidesurroundingthecells.(someendosporescanbeboiledforhoursandretaintheirviability),irradiation,strongacids,disinfectants,etc.Theyareprobablythemostdurablecellproducedinnature.Althoughcryptobiotic,theyretainviabilityindefinitelysuchthatunderappropriateenvironmentalconditions,theygerminatebackintovegetativecells.SporesBacterialendospores.Phasemicroscopyofsporulatingbacteriademonstratestherefractivityofendospores,aswellascharacteristicsporeshapesandlocationswithinthemothercell.ProkaryoteCellWallsFunctionsoftheBacteriacellwalls:•Theyareanessentialstructureforviability.•Theyarecomposedofuniquecomponentsfoundnowhereelseinnature.•Theyareoneofthemostimportantsitesforattackbyantibiotics.•Theyprovideligandsforadherenceandreceptorsitesfordrugsorviruses.•Theycausesymptomsofdiseaseinanimals.•Theyprovideforimmunologicaldistinctionandimmunologicalvariationamongstr