Sitoskeleton.ppt

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Cell Motility

Copyright (c) by W. H. Freeman and Company

Pergerakan sel Cytoskeleton -serabut protein yg ditemukan di sel eukariotik -support bentuk sel -menjaga organela pada lokasi yg tetap -membantu perpindahan material ke dalam sel Copyright (c) by W. H. Freeman and Company

Bagian sitoplasma, di antara organela penuh anyaman benang2 halus Disebut jala2 mikrotrabekula (mirip bunga karang) Krn membentuk kerangka sel shg disebut sitoskeleton

Copyright (c) by W. H. Freeman and Company

Cytoskeleton

Copyright (c) by W. H. Freeman and Company

The Cytoskeleton in Action

Sel darah putih menggunakan sitokeleton untuk “meraih” bacteri. Copyright (c) by W. H. Freeman and Company

The Cytoskeleton

An animal cell cytoskeleton Copyright (c) by W. H. Freeman and Company

The Cytoskeleton in Action

Cilia on a protozoan

Beating sperm tail at fertilization

Smoker’s cough is due to destruction of cilia linking the airways.

During blood clotting, platelets change shape due to changes in the actin cytoskeleton

Figure 18-8 Copyright (c) by W. H. Freeman and Company

Komponen Penyusun Sitoskeleton Protein yg di sitosol mmbentuk benang halus disbut filamen Ada 3 macam (berdasar struktur dan garis tengah) : mikrotubula (24 nm), mikrofilamen (60 Ao), filamen intermedia (8-10 nm)

Copyright (c) by W. H. Freeman and Company

19.6 Functions and structure of intermediate filaments distinguish them from other cytoskeletal fibers

Copyright (c) by W. H. Freeman and Company

Figure 19-50

mikrotubula Filamen dgn diameter trbesar (24 nm) Trsusun atas 13 protofilamen Tiap protofilamen tdr dr molekul2 tubulin (tubulin alfa dan beta) Punya kutub positif yg pertumbuhannya cepat, kutub negatif prtumbuhannya lambat Copyright (c) by W. H. Freeman and Company

Heterodimeric tubulin subunits compose the wall of a microtubule

Figure 19-2 Copyright (c) by W. H. Freeman and Company

19.1 Arrangement of protofilaments in singlet, doublet, and triplet microtubules

Figure 19-3 Copyright (c) by W. H. Freeman and Company

Berfungsi memberi bentuk sel, gerakan sel, menentukan bidng pembelahan sel Membentuk flagela, silia, sentriol

Copyright (c) by W. H. Freeman and Company

Mikrofilamen Trdiri dr mikrofilamen aktin, meosin dan tropomeosin (byk di otot) Aktin  aktin mrpkan protein kontraktil terbanyak di sel eukariotik Dalam bentuk monomer disebut Aktin G Dalam bentuk filamen disebut Aktin F Copyright (c) by W. H. Freeman and Company

Bersifat labil (mudah terakit dan terurai) Terlibat dlm proses sitokinesis, aliran plasma, gerakan sel, gerakan mikrovili intestinal

Copyright (c) by W. H. Freeman and Company

The actin cytoskeleton  Filamen aktin(or microfilaments) adalah salah satu dr 3 filamen protein yg menyusun system cytoskeleton  Eukaryotic cells contain abundant amounts of highly conserved actin

Copyright (c) by W. H. Freeman and Company

Figure 18-1

18.1 The actin cytoskeleton is organized into bundles and networks of filaments

Figure 18-4 Copyright (c) by W. H. Freeman and Company

Actin cross-linking proteins bridge actin filaments to form bundles and networks

Figure 18-5 Copyright (c) by W. H. Freeman and Company

Filamen Intermedia Bersifat liat Punya daya rentang tinggi. Benang berongga terdiri 5 protofilamen Diameter 8-10 nm Banyak terdapat di inti, dan sel yg alami stress mekanik spt epitelium, akson sel saraf dan otot polos Copyright (c) by W. H. Freeman and Company

Pergerakan otot/muscle

Copyright (c) by W. H. Freeman and Company

Microanatomy of Skeletal Muscle sel otot =

serabut otot yg mengandung myofibril

Copyright (c) by W. H. Freeman and Company

Muscle: a specialized contractile machine

Figure 18-26 Copyright (c) by W. H. Freeman and Company

Tiap serabut otot terdiri dari ribuan myofibril Tiap myofibril terdapat 1500 filamen meosin dan 3000 filamen aktin Tiap filamen meosin terdiri dari molekul meosin BM 33.200 dan molekul aktin BM 70.000

Copyright (c) by W. H. Freeman and Company

Dengan mikroskup cahaya : nampak gambaran gelap terang kepadatan relatif dan ada bagian yang tumpah tindih dr aktin dan miosin

Copyright (c) by W. H. Freeman and Company

Pita cahaya I Terdiri filamen aktin saja (nampak terang) Sifat terhadap cahaya yg terpolarisasi (berkas cahaya yg datang dipancarkan ke semua jurusan krn kepadatan sama)

I band Copyright (c) by W. H. Freeman and Company

Pita A Terletak dimana aktin dan meosin tumpang tindih (shg nampak gelap) Sifat anisotropik (cahaya dipancarkan tdk merata)

A band Copyright (c) by W. H. Freeman and Company

Sarkomer Terbentuk oleh 2 garis Z (protein nonkontraktil) atau sebuah pita A dan 2 belahan pita I Sarkoplasma Sitoplasma sel2 otot Terdapat retikulum sarkopasma agranuler

Copyright (c) by W. H. Freeman and Company

Z line

Z line

H band

Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company

Filamen meosin Tediri 2 utas peptid yg satu sama lainnya saling melilit dalam suatu heliks yg ujungnya membntuk kepala.

Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company

Filamen aktin Terdiri 3 unsur : troponin, tropomeosin, aktin

Copyright (c) by W. H. Freeman and Company

Active site : suatu molekul ADP dimana filamen meosin saling mengadakan interaksi dgn filamen aktin shg terjadi kontraksi otot

Tropomeosin : merupakan protein yg akan “menutupi” active site shg tdk terjadi kontraksi

Troponin : akan berikatan dgn Ca utk permulaan kontraksi

Copyright (c) by W. H. Freeman and Company

Ilustrasi sarkomer H Band

Copyright (c) by W. H. Freeman and Company

18.4 Capping proteins stabilize the ends of actin thin filaments in the sarcomere

Figure 18-28 Copyright (c) by W. H. Freeman and Company

18.4 Thick and thin filaments slide past one another during contraction

Figure 18-29 Copyright (c) by W. H. Freeman and Company

18.4 Titin and nebulin filaments organize the sarcomere

Figure 18-30 Copyright (c) by W. H. Freeman and Company

18.4 A rise in cytosolic Ca2+ triggers muscle contraction (part I)

Figure 18-31a Copyright (c) by W. H. Freeman and Company

18.4 A rise in cytosolic Ca2+ triggers muscle contraction (part II)

Figure 18-31b Copyright (c) by W. H. Freeman and Company

18.4 Tropomyosin and troponin regulate contraction in skeletal muscle

Figure 18-32 Copyright (c) by W. H. Freeman and Company

18.4 Ca2+-dependent mechanisms for regulating contraction in skeletal and smooth muscle

Figure 18-33 Copyright (c) by W. H. Freeman and Company

18.4 Myosin-dependent mechanisms also control contraction in some muscles

Figure 18-34 Copyright (c) by W. H. Freeman and Company

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