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Endoplasmic Reticulum Layers of Endoplasmic Reticulum with Attached Ribosomes

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Endoplasmic Reticulum Layers of Endoplasmic Reticulum with Attached Ribosomes TheThe CytoplasmCytoplasm Li Shulei [email protected] DepartmentDepartment ofof HistologyHistology && EmbryologyEmbryology CellCell componentscomponents CytoplasmCytoplasm PlasmaPlasma membranemembrane OrganellesOrganelles CytoplasmicCytoplasmic depositsdeposits CytoskeletonCytoskeleton CytosolCytosol (( MatrixMatrix )) NucleusNucleus PlasmaPlasma membranemembrane StructureStructure Thickness:7.5nm~10nmThickness:7.5nm~10nm UnitUnit membranemembrane FluidFluid mosaicmosaic modelmodel MainMain functionsfunctions TransmemebraneTransmemebrane transporttransport SignalSignal transmembranetransmembrane transductiontransduction PlasmaPlasma membranemembrane trilaminar appearance PlasmaPlasma membranemembrane Hydrophilic portion The ultrastructure and molecular organization of the cell membrane. The dark lines at left represent the two dense layers observed in the electron microscope. Cholesterol breaks up the close packing of phospholipid chains, and makes the membrane more fluid. The lipid composition of each half of the bilayer is different. PlasmaPlasma membranemembrane phospholipid integral double layer protein peripheraltransmembran proteineproteins A: The fluid mosaic model of membrane structure. B: Membrane cleavage occurs when cell is frozen and fractured into two parts along the hydrophobic interactions . PlasmaPlasma membranemembrane molecular structure of the plasma membrane. one-pass and multipass transmembrane proteins, peripheral protein proteins are present mainly in the cytoplasmic face. (1)(1) MitochondriaMitochondria StructureStructure Outer membrane Inner membrane Cristae: oxidative phosphorylation and electron transport system globular units: ADP to ATP Intermembrane space Intercristae space Matrix FunctionFunction Transform the chemical energy of the metabolites present in cytoplasm into energy that is easily accessible to the cell. MitochondriaMitochondria Outer membrane Inner membrane Crista Intercristae space Crista MitochondriaMitochondria C: Cristae M: Matrix protein-secreting cell Steroid-secreting cell flat, shelf-like cristae tubular cristae (2)Ribosomes(2)Ribosomes StructureStructure SmallSmall electronelectron--densedense particlesparticles TwoTwo differentdifferent--sizedsized subunitssubunits FreeFree ribosomeribosome ((PolyribosomePolyribosome)) && attachedattached ribosomeribosome IntenselyIntensely basophilicbasophilic FunctionFunction TakeTake partpart inin proteinprotein synthesissynthesis RibosomesRibosomes mRNAmRNA AminoAmino acid acid 2 1 protein protein RibosomesRibosomes RibosomesRibosomes More polyribosomes like curves and few single free ribosomes attached ribosomes attached ribosomes on the cytoplastic surface of endoplasmic reticulum Layers of Endoplasmic reticulum with attached ribosomes Because of developed attached ribosomes in cytoplasma, plasma cells is stained blue or basophilic in HE staining. (3)Endoplasmic(3)Endoplasmic ReticulumReticulum (ER)(ER) ConnectingConnecting andand branchingbranching channelschannels mademade byby aa continuouscontinuous membranemembrane ClassificationClassification RoughRough EndoplasmicEndoplasmic ReticulumReticulum (RER)(RER) SmoothSmooth EndoplasmicEndoplasmic ReticulumReticulum (SER)(SER) RoughRough EndoplasmicEndoplasmic ReticulumReticulum (RER)(RER) Distribution:Distribution: cellscells specialispecializedzed forfor proteinprotein secretionsecretion StructureStructure SaclikeSaclike andand parallelparallel stacksstacks ofof flattenedflattened cisternaecisternae PolyribosomesPolyribosomes onon thethe cytosoliccytosolic surfacesurface FunctionFunction synthesizsynthesiz proteinsproteins Intracellular storage (eg, in lysosomes) intracellular storage of proteins for export (eg, in pancreas) a component of other membranes (eg, integral proteins) PostPost--translationaltranslational modificationsmodifications ofof newlynewly formedformed polypeptidespolypeptides RoughRough EndoplasmicEndoplasmic ReticulumReticulum (RER)(RER) 3-D 2-D Saclike and parallel stacks of flattened cisternae Polyribosomes on the cytosolic surface It should be kept in mind that the cisternae appear separated in sections made for electron microscopy, but they form a continuous tunnel in the cytoplasm. SmoothSmooth EndoplasmicEndoplasmic ReticulumReticulum (SER)(SER) StructureStructure AppearAppear smoothsmooth andand lackslacks polyribosomespolyribosomes CisternaeCisternae areare tubulartubular oror vesiclevesicle FunctionFunction SynthesizesSynthesizes phospholipidsphospholipids forfor cellcell membranesmembranes ParticipatesParticipates inin synthesissynthesis ofof steroidsteroid hormoneshormones ParticipatesParticipates inin neutralizingneutralizing noxiousnoxious substancessubstances ParticipatesParticipates inin thethe utilizationutilization ofof glucoseglucose ParticipatesParticipates inin thethe contractioncontraction processprocess inin musclemuscle cellscells ((SarcoplasmicSarcoplasmic reticulum)reticulum) EndoplasmicEndoplasmic ReticulumReticulum 3-D The cisternae of SER are tubular and more likely to appear as vesicles in 2-D different shapes and sizes. (4)(4) GolgiGolgi ComplexComplex (Golgi(Golgi Apparatus)Apparatus) StructureStructure Small vesicles ( Transport vesicles ) Golgi cisternae Forming, convex, or cis face Maturing, concave, or trans face Large vacuoles ( Condensing vacuoles ) FunctionsFunctions Initiates packing, concentration, and storage of secretory products. Participates in post-translational modifications and limited proteolysis of proteins. GolgiGolgi ComplexComplex ((GolgiGolgi Apparatus)Apparatus) Large vacuoles Small vesicles plasma membrane receptor secretory vesicles lysosomes Near the cis face of Golgi complex, the RERs bud off small vesicles (transport vesicles) that shuttle newly synthesized proteins to the Golgi complex for further processing. The molecules are released from the Golgi trans face in larger vesicles to constitute secretory vesicles, lysosomes, or other cytoplasmic components. (5)(5) LysosomesLysosomes StructureStructure electron-dense, spherical, membrane-limited vesicles hydrolytic enzymes Function: intracytoplasmic digestion Origin:Origin: Enzymes are synthesized and segregated in RER, modified and packaged in Golgi complex LysosomesLysosomes FunctionsFunctions cells exhibiting phagocytic activity Digest material taken into the cell from its environment Concern the turnover of cytoplasmic organelles StructureStructure Primary lysosomes Secondary lysosome Residual bodies (lipofuscin, or age pigment ) LysosomesLysosomes pseudopod heterophagosome lysosomes There are many lysosomes in macrophage. nutrients primary lysosome fuses with the membrane of heterophagosome or autophagosomes. The composite structure is now termed secondary lysosome. After digestion, nutrients diffuse and enter the cytosol. residual bodies with indigestible compounds inside are retained. (6)(6) PeroxisomesPeroxisomes oror MicrobodiesMicrobodies StructureStructure characteristicscharacteristics SphericalSpherical membranemembrane--limitedlimited organellesorganelles withwith densedense corecore ContainContain catalasecatalase andand peroxydaseperoxydase FunctionFunction EliminateEliminate hydrogenhydrogen peroxideperoxide andand peroxidateperoxidate (2H(2H2OO2→→2H2H2O+OO+O2;;2RO22RO2→→2HO+O22HO+O2 )) DegradeDegrade toxictoxic moleculesmolecules inin liverliver andand kidneykidney ParticipateParticipate inin lipidlipid metabolismmetabolism FormationFormation ofof bilebile acidacid andand chelosterolchelosterol PeroxisomesPeroxisomes Round membrane-limited organelles with dense core (7)(7) CentrosomeCentrosome twotwo centriolescentrioles atat rightright anglesangles CentrioleCentriole:: cylindricalcylindrical structures;structures; ninenine setssets ofof microtubulesmicrotubules arrangedarranged inin triplets.triplets. FunctionFunction responsibleresponsible forfor formingforming thethe mitoticmitotic spindlespindle CentrioleCentriole && CentrosomeCentrosome Centriole shows nine sets of microtubules arranged in triplets. Centrosome is made of a pair of centrioles surrounded by a granular material CytoplasmicCytoplasmic depositsdeposits LipidLipid dropletsdroplets GlycogenGlycogen depositsdeposits SecretorySecretory granulesgranules oror secretorysecretory vesiclesvesicles PigmentsPigments (( LipofuscinLipofuscin )) LipidLipid dropletsdroplets Lipid droplets without membrane are different in size and electron lucent. GlycogenGlycogen depositsdeposits Glycogen Glycogen granules aggregate together, without limited- membrane, like flowers. S : secretory granules with limiting-membrane electron dense C : condensing vacuoles G : Golgi complex AgeAge pigmentspigments Brown age pigments on face Brown age pigments in cells CytoskeletonCytoskeleton StructureStructure componentscomponents MicrotubulesMicrotubules ActinActin filamentsfilaments (microfilaments)(microfilaments) IntermediateIntermediate filamentsfilaments FunctionsFunctions ProvideProvide forfor thethe shapingshaping ofof cellscells PlayPlay anan importantimportant rolerole inin thethe movementsmovements ofof organellesorganelles andand intracytoplasmicintracytoplasmic vesiclesvesicles ParticipateParticipate inin thethe movementmovement ofof cellscells StructureStructure ofof microtubulesmicrotubules Tubular,Tubular, outerouter diameterdiameter ofof 2424 nm,nm, aa densedense wallwall 55 nmnm thickthick ,, aa hollowhollow corecore 1414 nmnm wide.wide. heterodimerheterodimer:: ααandandββ tubulintubulin
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