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考研细胞生物学六章基质与内膜(上)课件.ppt


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该【考研细胞生物学六章基质与内膜(上)课件 】是由【rdwiirh】上传分享,文档一共【31】页,该文档可以免费在线阅读,需要了解更多关于【考研细胞生物学六章基质与内膜(上)课件 】的内容,可以使用淘豆网的站内搜索功能,选择自己适合的文档,以下文字是截取该文章内的部分文字,如需要获得完整电子版,请下载此文档到您的设备,方便您编辑和打印。考研资料北京大学细胞生物学第六章基质与内膜(上)

Membranesdividethecytoplasmofeukaryoticcellsintodistinctcompartments.
Threecategoriesineukaryoticcells:
(1)theendomembranesystem:ER,Golgicomplex,Lys.,
secretoryvesicles.
(2)thecytosol.
(3)mitochondria,chloroplasts,peroxisomes,andthenucleus.
Membrane-boundstructures(organelles)arefoundinalleukaryoticcells.

Insightsgainedfromautoradiography;
Insightsgainedfromthebiochemicalanalysisofsubcellularfractions;
Insightsgainedfromthestudyofgeneticmutants;
Thedynamicactivitiesofendomembranesystemsarehighlyconserveddespitethestructuraldiversityofdifferentcelltypes.
DeDuve,,1974NobelPlrize

Reticulum(ER)
RoughendoplasmicreticulumandSmoothendoplasmicreticulum
RERhasribosomesonthecytosolicsideofcontinuous,flattenedsacs(cisternae);SERisaninterconnectingnetworkoftubularmembraneelements.
Microsome(100-200nm)
rERofpancreaticcells
Microsomesareheterogeneousmixturesofsimilar-sizedvesicles,,allowingstudiesoffunctionandcomposition.

ProteinssynthesizedonribosomesofrERinclude:
secretoryproteins,
integralmembraneproteins,
solubleproteinsoforganelles.
Modificationandprocessingofnewlysynthesizedproteins:glycosylationintherER;
N-linked:linkedtotheamidenitrogenofasparagine(ER)
O-linked:linkedtothehydroxylgroupserineorthreonineviaGalNac(inGolgi)
Theprecursorof14residuesisthesameinplants,animals,andsingle-celledeukaryotes
thenremove3glucosesand1mannoseintheER
Qualitycontrolofofnewlysynthesizedproteins---TheroleofN-linkedglycosylationinERproteinfolding
Qualitycontrol:ensuringthatmisfoldedproteinsdonotleaveER
ThelumenofrERcontains:
Bipandcalnexin(chaperones):thatrecognizeandbindtounfoldedormisfoldedproteinsandgivethemcorrectconformation;
Proteindisulfideisomerase(PDI);
GT(glucosyl-transferase,monitoringenenzyme)recognizeunfoldedormisfoldedproteinsandaddsaglucosetotheendofoligo..
Synthesisofmembranelipids
MostmembranelipidsaresynthesizedenterlywithintheER.
Therearetwoexceptions:
sphingomyelinandglycolipids,(beginsinER;completedinGolgi);
(2)someoftheuniquelipidsoftheMitandChlmembranes(themself).
Themembranesofdifferent0rganelleshavemarkedlydifferentlipidscomposition.
Transportbybudding:ER→GC、Ly、PM
Transportbyphospholipidexchangeproteins(PEP):ER→otherorganelles(includingMitandChl)

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  • 时间2023-03-18