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ID:39155560
大小:490.00 KB
页数:9页
时间:2019-06-25
《Electron Transfer Chain》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、Electrontransportchain1ElectrontransportchainAnelectrontransportchain(ETC)coupleselectrontransferbetweenanelectrondonor(suchasNADH)andanelectronacceptor(suchasO2)withthetransferofH+ions(protons)acrossamembrane.Theresultingelectrochemicalprotongradientisuse
2、dtogeneratechemicalenergyintheformofadenosinetriphosphate(ATP).Electrontransportchainsarethecellularmechanismsusedforextractingenergyfromsunlightinphotosynthesisandalsofromredoxreactions,suchastheoxidationofsugars(respiration).Inchloroplasts,lightdrivesthe
3、conversionofwatertooxygenandNADP+toNADPHwithtransferofH+Theelectrontransportchaininthemitochondrionisthesiteofoxidativephosphorylationionsacrosschloroplastmembranes.Inineukaryotes.TheNADHandsuccinategeneratedinthecitricacidcycleareoxidized,mitochondria,iti
4、stheconversionofprovidingenergytopowerATPsynthase.oxygentowater,NADHtoNAD+andsuccinatetofumaratethatarerequiredtogeneratetheprotongradient.Electrontransportchainsaremajorsitesofprematureelectronleakagetooxygen,generatingsuperoxideandpotentiallyresultingini
5、ncreasedoxidativestress.BackgroundTheelectrontransportchainconsistsofaspatiallyseparatedseriesofredoxreactionsinwhichelectronsarePhotosyntheticelectrontransportchainofthethylakoidmembrane.transferredfromadonormoleculetoanacceptormolecule.Theunderlyingforce
6、drivingthesereactionsistheGibbsfreeenergyofthereactantsandproducts.TheGibbsfreeenergyistheenergyavailable("free")todowork.AnyreactionthatdecreasestheoverallGibbsfreeenergyofasystemisthermodynamicallyspontaneous.Thefunctionoftheelectrontransportchainistopro
7、duceatransmembraneprotonelectrochemicalgradientasaresultoftheredoxreactions.[1]Ifprotonsflowbackthroughthemembrane,theyenablemechanicalwork,suchasrotatingbacterialflagella.ATPsynthase,anenzymehighlyconservedamongalldomainsoflife,convertsthismechanicalworki
8、ntochemicalenergybyproducingATP,[2]whichpowersmostcellularreactions.SmallamountofATPisavailablefromsubstrate-levelphosphorylation,forexample,inglycolysis.InmostorganismsthemajorityofElectrontransportchain2ATP
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