Clase 03 - Citoplasma y Citoesqueleto Motilidad Celular y Estructura de Cilios y Flagelos (8 de Septiembre 2008)

7/31/2019 Clase 03 - Citoplasma y Citoesqueleto Motilidad Celular y Estructura de Cilios y Flagelos (8 de Septiembre 2008)

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Citoplasma y citoesqueleto.Motilidad celular. Estructura de

cilios y flagelos

ESME110


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Evolution of cells Present-day cells evolved from a common prokaryotic ancestor along threelines of descent, giving rise to archaebacteria, eubacteria, and eukaryotes. Mitochondria andchloroplasts originated from the endosymbiotic association of aerobic bacteria andcyanobacteria, respectively, with the ancestors of eukaryotes.

3.8 billones

Metabolismooxidativo

2.7 billones

Organizacin ms compleja:

- organelas membranosas

- citoesqueleto

Eficiencia energtica


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The major features of eucaryotic cells. The drawing depicts a typical animal cell, but almost all thesame components are found in plants and fungi and in single-celled eucaryotes such as yeasts andprotozoa. Plant cells contain chloroplasts in addition to the components shown here, and their plasmamembrane is surrounded by a tough external wall formed of cellulose.


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Hypotheses for the evolutionary origins of some membrane-bounded organelles. The origins of mitochondria, chloroplasts, ER, and the cellnucleus could explain the topological relationships of these intracellular compartments in eucaryotic cells. (A) A possible pathway for the evolution ofthe cell nucleus and the ER. In some bacteria the single DNA molecule is attached to an invagination of the plasma membrane, called a mesosome.Such an invagination in a very ancient procaryotic cell could have spread to form an envelope around the DNA while still allowing access of the DNAto the cell cytosol (as is required for DNA to direct protein synthesis). This envelope is presumed to have eventually pinched off completely from theplasma membrane, producing a nuclear compartment surrounded by a double membrane. As illustrated, the nuclear envelope is organized by afibrous shell called the nuclear laminaand is penetrated by communicating channels called nuclear pore complexes. Because it is surrounded by twomembranes that are in continuity where they are penetrated by these pores, the nuclear compartment is topologically equivalent to the cytosol. Thelumen of the ER is continuous with the space between the inner and outer nuclear membranes and topologically equivalent to the extracellular space.(B) Mitochondria (and chloroplasts) are thought to have originated when a bacterium was engulfed by a larger pre-eucaryotic cell. They retain their

autonomy. This may explain why the lumens of these organelles remain isolated from the vesicular traffic that interconnects the lumens of many otherintracellular compartments.

Citosol

Agua: 75 a 80%

Electrolitos: K, Mg, P, S, Na, Cl,Ca,etcProtenas: 10 a 15%LpidosCarbohidratos: glucgeno


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200 tipos celulares diferentes

5 tipos principales de tejidos: (1) epitelial; (2)

conectivo; (3) muscular; (4) nervioso; (5)sangre

5 compartimentos intracelulares: (1) elncleo y el citosol; (2) organelas quefuncionan en la va secretoria y endoctica;(3) mitocondria; (4) cloroplastos (c. vegetal);(5) peroxisomas

Las clulas NO pueden sintetizar organelasde novo.

Cada clula tiene un desarrollo de organelas

adecuado a su funcin.


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Todas las protenas se sintetizan en el citosol

Ribosomas asociados al RERibosomas libres (polisomas)

i) Protenas que quedan asociadas alas membranas (protenas integrales,ancladas y asociadas: receptores,canales, etc.).

ii) Protenas que quedan enel lumen del RER o el Golgi.

iii) Protenas destinadas a otrasorganelas (lisomas).

iv) Protenas secretorias.


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El destino de la proteina esta determinado por su secuencia:


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citoesqueleto

Red de filamentos proteicos, que confierenforma y organizacin interna a la clula ypermiten su movimiento (total y el deorganelas).

Estructura dinmica

1.- Microfilamentos (actina)

2.- Filamentos intermedios3.- Microtbulos (tubulina)

Protenas accesorias


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Polmeros de actina 7 nm de dimetro Concentrados en la

periferia de la clula Se organizan en

estructuras complejas(redes tridimensionales)

Contribuyen almantenimiento de la formay polaridad celular

Forman pseudopodios ymicrovellosidades (migrar y

fagocitar compuestos) Forman uniones clula-

clula y clula-matrizextracelular (sealizacinintracelular)


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Assembly and structure of actinfilaments (A) Actin monomers (G actin)polymerize to form actin filaments (Factin). The first step is the formation ofdimers and trimers, which then grow bythe addition of monomers to both ends.(C, courtesy of Dan Richardson.)Reversible polymerization of actin

monomers

Frmacos:

Citocalasina.- se une al extremo +endy bloquea la elongacin

Faloidina.- se une a los filamentos deactina e inhibe su disociacin

Protenas de unin a actina

Profilina .- favoroce la polimerizacin

Cofilina.- favorece el desemsamblaje

Arp2/3 (sitios de nucleacin=inicio delensamblaje)

Distrofina (distrofia muscular)

43 kDa

Polimerizacin reversible, ATP

ATP

ADP

ATPATP

ATP ADP

ATP

ATP

Filamento polar


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Cell surface projections involved in phagocytosis andmovement. Lamelopodios, pseudopodos, filopodios


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Structure of intermediate filament proteins Intermediate filament proteins contain a central-helical rod domain of approximately 310 amino acids (350 amino acids in the nuclear

lamins). The N-terminal head and C-terminal tail domains vary in size and shape.

A pesar de la diversidad, las protenas que forman FI tienen una estructura comn conservada


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Assembly of intermediate filaments The central rod domains of two polypeptides windaround each other in a coiled-coil structure to form dimers. Dimers then associate in astaggered antiparallel fashion to form tetramers. Tetramers associate end to end to formprotofilaments and laterally to form filaments. Each filament contains approximately

eight protofilaments wound around each other in a ropelike structure. Phosphorylation.


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Experimental demonstration of keratin functionA plasmid encoding a mutant keratin that interfereswith the normal assembly of keratin filaments wasmicroinjected into one pronucleus of a fertilized egg.Microinjected embryos were then transferred to a

foster mother, and some of the offspring were foundto have incorporated the mutant keratin gene intotheir genome. Expression of the mutant gene inthese transgenic mice disrupted the keratincytoskeleton of cells of the epidermis, resulting insevere skin blistering due to cell lysis following mildmechanical stress

Esclerosis lateral amiotrfica(ALS). Enfermedad de LouGehring (Stephen Hawking).

Acumulacin y ensamblajeanormal de neurofilamentos.


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Componentes msgrandes del citoesqueleto

Cilindros huecos de aprox.25 nm de dimetro

polmeros de y tubulina (isoformas)

Participan:

-Transporte intracelular

- Cilios y flagelos- Divisin celular


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Dynamic instability of microtubules Dynamic instability results from the hydrolysis of GTP bound to -tubulin during orshortly after polymerization, which reduces its binding affinity for adjacent molecules. Growth of microtubules continues aslong as there is a high concentration of tubulin bound to GTP. New GTP-bound tubulin molecules are then added morerapidly than GTP is hydrolyzed, so a GTP cap is retained at the growing end. However, if GTP is hydrolyzed more rapidlythan new subunits are then added, the presence of GDP-bound tubulin at the end of the microtubule leads to disassemblyand shrinkage. Only the plus ends of microtubules are illustrated.

Postranslation modifications.- Acetylation. Detyrosination (MT maduration): (1) clock; (2)sitios de unin a MAPs


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Intracellular organization of microtubules The minus

ends of microtubules are anchored in the centrosome. Ininterphase cells, the centrosome is located near thenucleus and microtubules extend outward to the cellperiphery. During mitosis, duplicated centrosomes separateand microtubules reorganize to form the mitotic spindle.

Colchicina.- previene la polimerizacin.

Taxol.- se une a los MT y los estabiliza; impide la

despolimerizacin.


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Structure of the axoneme of cilia and flagella. (B) Schematic cross section of anaxoneme. The nine outer doublets consist of one complete (A) and one incomplete(B) microtubule, containing only 10 or 11 protofilaments. The outer doublets arejoined to each other by nexin links and to the central pair of microtubules by radialspokes. Each outer microtubule doublet is associated with inner and outer dyneinarms. (A, K. G. Murti/Visuals Unlimited.)


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El mal funcionamiento de cilios y flagelos produce enfermedades


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Proteins of the cytoskeleton

Microfilaments Actins - Actin-binding proteins - Actinin - Arp2/3 complex -

Cofilin - Destrin- Gelsolin - Myosins - Profilin - Tropomodulin -Troponin (T, C, I) - Tropomyosin - Wiskott-Aldrich syndromeprotein

Intermediatefilaments

type 1and 2(Cytokeratin, type I, type II) - type3(Desmin,GFAP, Peripherin, Vimentin) - type4(Internexin, Nestin,

Neurofilament) - type5(LaminA, B)

Microtubules Dyneins - Kinesins - MAPs (Tau protein, Dynamin) - Tubulins -

Catenins Alpha catenin - Beta catenin - Plakoglobin (gamma catenin) -Delta catenin

Other APC - Dystrophin(Dystroglycan) - plakin(Desmoplakin, Plectin)- Spectrin - Talin - Utrophin - Vinculin
http://en.wikipedia.org/wiki/Cofilinhttp://en.wikipedia.org/wiki/Destrinhttp://en.wikipedia.org/wiki/Gelsolinhttp://en.wikipedia.org/wiki/Myosinhttp://en.wikipedia.org/wiki/Myosinhttp://en.wikipedia.org/wiki/Myosinhttp://en.wikipedia.org/wiki/Profilinhttp://en.wikipedia.org/wiki/Profilinhttp://en.wikipedia.org/wiki/Tropomodulinhttp://en.wikipedia.org/wiki/Tropomodulinhttp://en.wikipedia.org/wiki/Troponinhttp://en.wikipedia.org/wiki/Troponinhttp://en.wikipedia.org/wiki/Troponin_Thttp://en.wikipedia.org/wiki/Troponin_Chttp://en.wikipedia.org/wiki/Troponin_Ihttp://en.wikipedia.org/wiki/Tropomyosinhttp://en.wikipedia.org/wiki/Tropomyosinhttp://en.wikipedia.org/wiki/Tropomyosinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Intermediate_filamenthttp://en.wikipedia.org/wiki/Glial_fibrillary_acidic_proteinhttp://en.wikipedia.org/wiki/Peripherinhttp://en.wikipedia.org/wiki/Peripherinhttp://en.wikipedia.org/wiki/Peripherinhttp://en.wikipedia.org/wiki/Vimentinhttp://en.wikipedia.org/wiki/Vimentinhttp://en.wikipedia.org/wiki/Vimentinhttp://en.wikipedia.org/wiki/Internexinhttp://en.wikipedia.org/wiki/Internexinhttp://en.wikipedia.org/wiki/Internexinhttp://en.wikipedia.org/wiki/Nestin_(protein)http://en.wikipedia.org/wiki/Nestin_(protein)http://en.wikipedia.org/wiki/Neurofilamenthttp://en.wikipedia.org/wiki/Neurofilamenthttp://en.wikipedia.org/wiki/Neurofilamenthttp://en.wikipedia.org/wiki/Laminhttp://en.wikipedia.org/wiki/Laminhttp://en.wikipedia.org/wiki/Laminhttp://en.wikipedia.org/wiki/LMNAhttp://en.wikipedia.org/wiki/Lamin_Bhttp://en.wikipedia.org/wiki/Dyneinhttp://en.wikipedia.org/wiki/Kinesinhttp://en.wikipedia.org/wiki/Kinesinhttp://en.wikipedia.org/wiki/Kinesinhttp://en.wikipedia.org/wiki/Microtubule-associated_proteinhttp://en.wikipedia.org/wiki/Microtubule-associated_proteinhttp://en.wikipedia.org/wiki/Microtubule-associated_proteinhttp://en.wikipedia.org/wiki/Tau_proteinhttp://en.wikipedia.org/wiki/Tau_proteinhttp://en.wikipedia.org/wiki/Tau_proteinhttp://en.wikipedia.org/wiki/Tau_proteinhttp://en.wikipedia.org/wiki/Tau_proteinhttp://en.wikipedia.org/wiki/Tau_proteinhttp://en.wikipedia.org/wiki/Delta_cateninhttp://en.wikipedia.org/wiki/Spectrinhttp://en.wikipedia.org/wiki/Spectrinhttp://en.wikipedia.org/wiki/Spectrinhttp://en.wikipedia.org/wiki/Talin_(protein)http://en.wikipedia.org/wiki/Utrophinhttp://en.wikipedia.org/wiki/Utrophinhttp://en.wikipedia.org/wiki/Vinculinhttp://en.wikipedia.org/wiki/Vinculinhttp://en.wikipedia.org/wiki/Vinculinhttp://en.wikipedia.org/wiki/Vinculinhttp://en.wikipedia.org/wiki/Utrophinhttp://en.wikipedia.org/wiki/Talin_(protein)http://en.wikipedia.org/wiki/Spectrinhttp://en.wikipedia.org/wiki/Plectinhttp://en.wikipedia.org/wiki/Desmoplakinhttp://en.wikipedia.org/wiki/Dystroglycanhttp://en.wikipedia.org/wiki/Dystrophinhttp://en.wikipedia.org/wiki/APC_(gene)http://en.wikipedia.org/wiki/Delta_cateninhttp://en.wikipedia.org/wiki/Plakoglobinhttp://en.wikipedia.org/wiki/Beta-cateninhttp://en.wikipedia.org/wiki/Alpha_cateninhttp://en.wikipedia.org/wiki/Cateninhttp://en.wikipedia.org/wiki/Tubulinhttp://en.wikipedia.org/wiki/Dynaminhttp://en.wikipedia.org/wiki/Tau_proteinhttp://en.wikipedia.org/wiki/Microtubule-associated_proteinhttp://en.wikipedia.org/wiki/Kinesinhttp://en.wikipedia.org/wiki/Dyneinhttp://en.wikipedia.org/wiki/Microtubulehttp://en.wikipedia.org/wiki/Lamin_Bhttp://en.wikipedia.org/wiki/LMNAhttp://en.wikipedia.org/wiki/Laminhttp://en.wikipedia.org/wiki/Neurofilamenthttp://en.wikipedia.org/wiki/Nestin_(protein)http://en.wikipedia.org/wiki/Internexinhttp://en.wikipedia.org/wiki/Vimentinhttp://en.wikipedia.org/wiki/Peripherinhttp://en.wikipedia.org/wiki/Glial_fibrillary_acidic_proteinhttp://en.wikipedia.org/wiki/Desminhttp://en.wikipedia.org/wiki/Type_II_keratinhttp://en.wikipedia.org/wiki/Type_I_keratinhttp://en.wikipedia.org/wiki/Cytokeratinhttp://en.wikipedia.org/wiki/Intermediate_filamenthttp://en.wikipedia.org/wiki/Intermediate_filamenthttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Wiskott-Aldrich_syndrome_proteinhttp://en.wikipedia.org/wiki/Tropomyosinhttp://en.wikipedia.org/wiki/Troponin_Ihttp://en.wikipedia.org/wiki/Troponin_Chttp://en.wikipedia.org/wiki/Troponin_Thttp://en.wikipedia.org/wiki/Troponinhttp://en.wikipedia.org/wiki/Tropomodulinhttp://en.wikipedia.org/wiki/Profilinhttp://en.wikipedia.org/wiki/Myosinhttp://en.wikipedia.org/wiki/Gelsolinhttp://en.wikipedia.org/wiki/Destrinhttp://en.wikipedia.org/wiki/Cofilinhttp://en.wikipedia.org/wiki/Arp2/3_complexhttp://en.wikipedia.org/wiki/Actininhttp://en.wikipedia.org/wiki/Actin-binding_proteinhttp://en.wikipedia.org/wiki/Actin-binding_proteinhttp://en.wikipedia.org/wiki/Actin-binding_proteinhttp://en.wikipedia.org/wiki/Actinhttp://en.wikipedia.org/wiki/Microfilament

Documents

Clase 03 - Citoplasma y Citoesqueleto Motilidad Celular y Estructura de Cilios y Flagelos (8 de Septiembre 2008)