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 molecules.molecules. †† 1313 tubulintubulin unitsunits organizedorganized intointo aa spiralspiral inin oneone turn.turn. †† growgrow fromfrom microtubulemicrotubule--organizingorganizing centerscenters MicrotubulesMicrotubules

Transverse section Aggregated small rings

Longitudinal section Long and thin tubules FunctionsFunctions ofof microtubulesmicrotubules

†† keepkeep cellcell’’ss shapeshape †† intracellularintracellular transporttransport ofof organellesorganelles andand vesicles.vesicles. MicrofilamentsMicrofilaments ((ActinActin filaments)filaments)

†† StructureStructure „„ AboutAbout 5~7nm5~7nm inin diameterdiameter „„ globularglobular subunitssubunits „„ doubledouble--strandedstranded †† FunctionFunction „„ maintainmaintain thethe shapeshape ofof cellcell „„ contraction,contraction, movement,movement, mitoticmitotic divisiondivision MicrotubulesMicrotubules && MicrofilamentsMicrofilaments

Microfilaments are much thinner than microtubules. IntermediateIntermediate FilamentsFilaments

†† diameterdiameter ofof 1010--1212 nm.nm. †† keratinkeratin filaments:filaments: epithelialepithelial cellscells †† desmindesmin filaments:filaments: musclemuscle cellscells †† vimentinvimentin filaments:filaments: fibroblasts,fibroblasts, mesenchymalmesenchymal cellscells †† NeurofilamentsNeurofilaments:: neuronsneurons †† neuroglialneuroglial filaments:filaments: astrocytesastrocytes IntermediateIntermediate FilamentsFilaments

immunofluorescence: desmin filaments （yellow meshwork）in decidual cell

EM: keratin filaments （bundle of thin threads） in epithelial cell CytosolCytosol

†† ComponentsComponents „„ WaterWater „„ EnzymesEnzymes toto synthesizesynthesize andand decomposedecompose moleculesmolecules „„ MachineryMachinery toto synthesizesynthesize proteinsproteins †† FunctionsFunctions „„ CoordinateCoordinate thethe intracellularintracellular movementsmovements ofof organellesorganelles „„ ProvideProvide aa frameworkframework forfor thethe organizationorganization ofof enzymeenzyme andand substratessubstrates OverviewOverview ofof nucleusnucleus †† intenseintense basophilicbasophilic inin HEHE sectionsection †† replicatereplicate DNADNA †† synthesizesynthesize andand processprocess RNAsRNAs

A basophilic nucleus with a developed nucleolus is located in the center of the acidophilic cytoplasm. NucleusNucleus

†† MainMain componentscomponents „„ NuclearNuclear envelopeenvelope „„ ChromatinChromatin „„ NucleolusNucleolus „„ NuclearNuclear matrixmatrix NuclearNuclear EnvelopeEnvelope

†† OuterOuter nuclearnuclear membranemembrane †† InnerInner nuclearnuclear membranemembrane †† PerinuclearPerinuclear cisternacisterna †† FibrousFibrous laminalamina †† NuclearNuclear porespores

RNA protein NuclearNuclear EnvelopeEnvelope Nuclear envelope Outer nuclear membrane

Inner nuclear membrane Nuclear pores Nuclear pores

Nucleus

Fibrous lamina Perinuclear cisterna ChromatinChromatin †† ComponentsComponents „„ DNADNA && ProteinsProteins †† ClassificationClassification „„ Heterochromatin:Heterochromatin: inactiveinactive cellscells †† LMLM:: basophilicbasophilic clumpsclumps †† EMEM:: coarsecoarse granulesgranules „„ EuchromatinEuchromatin:: activeactive cellscells †† LMLM:: lightlylightly stainedstained basophilicbasophilic areasareas †† EMEM:: finelyfinely disperseddispersed granulargranular materialmaterial NucleusNucleus

Euchromatin

Nucleolus

Heterochromatin

HE staining EM NucleolusNucleolus †† SphericalSpherical structurestructure †† RichRich inin rRNArRNA andand proteinprotein (forming(forming ribosomesribosomes)) †† BasophilicBasophilic whenwhen stainedstained withwith HH && EE †† largerlarger andand moremore inin proteinprotein--secretingsecreting cellscells

HE staining NuclearNuclear matrixmatrix

†† betweenbetween thethe chromatinchromatin andand thethe nucleolinucleoli †† nuclearnuclear hyaloplasmhyaloplasm „„ water,water, ionsions andand enzymesenzymes †† NucleoskeletonNucleoskeleton „„ 3D3D meshworkmeshwork „„ proteinsproteins „„ connectsconnects withwith nuclearnuclear fibrousfibrous laminalamina „„ proteinprotein basebase toto whichwhich DNADNA loopsloops areare boundbound SummarySummary

†† MasterMaster thethe structurestructure andand functionfunction ofof mitochondrionmitochondrion ,, polyribosomepolyribosome ,, RERRER ,, SER,SER, GolgiGolgi complexcomplex ,, lysosomelysosome,, microbodymicrobody,, cytoskeletoncytoskeleton andand nucleus.nucleus. †† UnderstandUnderstand thethe structurestructure componentscomponents ofof plasmaplasma membranemembrane andand thethe conceptconcept ofof unitunit membranemembrane..