植物学及园艺学英文版 botany and horticulture 20

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1、EnergeticsEnergydefinedasthecapacitytodoworkTwoformsofenergy:PotentialEnergy=StoredEnergyKineticEnergy=EnergythatisdoingworkThermodynamicsThestudyofenergytransformations2Laws1stlawtalksaboutconvertingenergy2ndlawtalksaboutwhathappenstotheenergy(Kinetic)duringthisconversionRobbingPetertopayPaul1s

2、tlawthermodynamicstotalenergyinuniverseisconstantEtodoworkcan'tbegeneratedfromnothingitmustbeobtainedfromoutsidethesystemlosesacorrespondingamountofEtobalancethebooksWorldisgoingdownhill2ndlawthermodynamicsWheneveranythingactuallyhappens,theentropy(disorder)ofthesystem(oroftheuniverse)increases(ca

3、nnotdecrease)EntropyisameasureoftheamountofenergythatbecomesunavailableforusefulworkDisordermaybeinthearrangementofmatterorenergy–Heat(thermalenergy)isdisorderedenergyHowcanlifeexist?LifeisanorganizationofmatterAsystematicDECREASEinentropyViolatesthe2ndlawofthermodynamics!!Organizingprocessesrequi

4、reenergySteadyinputofenergyfromthesunLifeisaseriesofenergytransfersLifedependsonthefactthatenergycanbeconvertedfrom1formtoanotherCHEMICALCYCLE─PhotosynthesisCO2+H2OC6H12O6+O2Respiration───LightenergyisconvertedintopotentialEnergyofGlucose(Ps)orthispotentialEnergyistransformedintoKineticEnergy(Re

5、spiration)andwhensomeoftheenergystoredintheglucosemoleculeismadeavailableforcellularwork)MetabolismLivingcell=chemicalfactoryorganicmoleculesbrokendownreleasingtheenergyintheirbonds&newmoleculesaresynthesizedMetabolism=catabolism+anabolismcatabolism-complexmoleculesbrokenintosimpleronesanabolism-

6、complexmoleculesconstructedoutofsimpleronesEnzymes(ase)Mostreactionsrequireinitialenergytoproceed(ACTIVATIONENERGY)DecreasenecessaryactivationenergyCo-factorsmaybeused(changesshapeofenzyme–excitatoryorinhibitory–allostericregulation)Nicotinamideadeninedinucleotide(NAD)-niacinNolossofenzymeShapecri

7、ticalEnzymes•formationof:enzyme-substratecomplex•substrateoptimalpositiontoreact(stressonbonds-orientation)•AfterreactionreleaseofenzymeE+SE-SE+PSubstrateActiveSiteInducedFitEnzymeInhibitors1.Competitiveinhibi