1. Copyright (c) by W. H. Freeman and Company Chapter 18 Cell Motility and Shape I: Microfilaments

2. Copyright (c) by W. H. Freeman and Company 18.1 The actin cytoskeleton  Actin filaments (or microfilaments) are one of the three protein filament systems that comprise the cytoskeleton  Eukaryotic cells contain abundant amounts of highly conserved actin Figure 18-1

3. Copyright (c) by W. H. Freeman and Company 18.1 ATP holds together the two lobes of the actin monomer Figure 18-2a

4. Copyright (c) by W. H. Freeman and Company 18.1 G-actin assembles into long, helical F-actin polymers Figure 18-2b,c

5. Copyright (c) by W. H. Freeman and Company 18.1 The actin cytoskeleton is organized into bundles and networks of filaments Figure 18-4

6. Copyright (c) by W. H. Freeman and Company 18.1 Actin cross-linking proteins bridge actin filaments to form bundles and networks Figure 18-5

7. Copyright (c) by W. H. Freeman and Company 18.1 Cortical actin networks are connected to the plasma membrane: erythrocytes Figure 18-7

8. Copyright (c) by W. H. Freeman and Company 18.1 During blood clotting, platelets change shape due to changes in the actin cytoskeleton Figure 18-8

9. Copyright (c) by W. H. Freeman and Company 18.1 Cross-linkage of actin filament networks to the plasma membrane in various cells Figure 18-9

10. Copyright (c) by W. H. Freeman and Company 18.1 Actin bundles support projecting fingers of membrane Figure 18-10

11. Copyright (c) by W. H. Freeman and Company 18.2 Actin polymerization in vitro proceeds in three steps Figure 18-11 Animação

12. Copyright (c) by W. H. Freeman and Company 18.2 Actin filaments grow faster at one end that at the other Figure 18-13 Several toxins can disrupt the actin monomer-polymer equilibrium

13. Copyright (c) by W. H. Freeman and Company 18.2 Actin polymerization is regulated by proteins that bind G-actin Figure 18-15a,b

14. Copyright (c) by W. H. Freeman and Company 18.2 Many movements are driven by actin polymerization The acrosome reaction in echinoderm sperm Figure 18-17

15. Copyright (c) by W. H. Freeman and Company 18.2 Movement of intracellular bacteria and viruses depends on actin polymerization Figure 18-18

16. Copyright (c) by W. H. Freeman and Company 18.2 Actin polymerization at the leading edge of moving cells Figure 18-19 Actin Dinamics in moving cells Actin in Lamelipodia Movements

17. Copyright (c) by W. H. Freeman and Company 18.3 Myosin: the actin motor protein All myosins have head, neck, and tail domains with distinct functions Figure 18-20

18. Copyright (c) by W. H. Freeman and Company 18.3 Functions of the myosin tail domain Figure 18-21

19. Copyright (c) by W. H. Freeman and Company 18.3 Myosin heads walk along actin filaments Figure 18-22 animação

20. Copyright (c) by W. H. Freeman and Company 18.3 Myosin and kinesin share the Ras fold with certain signaling proteins Figure 18-24

21. Copyright (c) by W. H. Freeman and Company 18.3 Conformational changes in the myosin head couple ATP hydrolysis to movement Figure 18-25 animação

22. Copyright (c) by W. H. Freeman and Company 18.4 Muscle: a specialized contractile machine Figure 18-26

23. Copyright (c) by W. H. Freeman and Company 18.4 Skeletal muscle contains a regular array of actin and myosin Figure 18-27

24. 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

25. Copyright (c) by W. H. Freeman and Company 18.4 Thick and thin filaments slide past one another during contraction Figure 18-29

26. Copyright (c) by W. H. Freeman and Company 18.4 Titin and nebulin filaments organize the sarcomere Figure 18-30

27. Copyright (c) by W. H. Freeman and Company 18.4 A rise in cytosolic Ca 2+ triggers muscle contraction (part I) Figure 18-31a

28. Copyright (c) by W. H. Freeman and Company 18.4 A rise in cytosolic Ca 2+ triggers muscle contraction (part II) Figure 18-31b

29. Copyright (c) by W. H. Freeman and Company 18.4 Tropomyosin and troponin regulate contraction in skeletal muscle Figure 18-32

30. Copyright (c) by W. H. Freeman and Company 18.4 Ca 2+ -dependent mechanisms for regulating contraction in skeletal and smooth muscle Figure 18-33

31. Copyright (c) by W. H. Freeman and Company 18.4 Myosin-dependent mechanisms also control contraction in some muscles Figure 18-34

32. Copyright (c) by W. H. Freeman and Company 18.5 Actin and myosin II are arranged in contractile bundles that function in cell adhesion Figure 18-35

33. Copyright (c) by W. H. Freeman and Company 18.5 Myosin II stiffens cortical membranes Figure 18-36

34. Copyright (c) by W. H. Freeman and Company 18.5 Actin and myosin II have essential roles in cytokinesis Figure 18-37

35. Copyright (c) by W. H. Freeman and Company 18.6 Controlled polymerization and rearrangements of actin filaments occur during keratinocyte movement Figure 18-41 Video Animação

36. Copyright (c) by W. H. Freeman and Company 18.6 A model of the molecular events at the leading edge of a moving cell Figure 18-42

37. Copyright (c) by W. H. Freeman and Company 18.6 Myosin I and myosin II have important roles in cell migration Figure 18-43

38. Copyright (c) by W. H. Freeman and Company 18.6 Changes in localization of cytosolic Ca 2+ during cell location Figure 18-45

39. Copyright (c) by W. H. Freeman and Company Chapter 19 Cell Motility and Shape II: Microtubules and Intermediate Filaments

40. Copyright (c) by W. H. Freeman and Company 19.1 Heterodimeric tubulin subunits compose the wall of a microtubule Figure 19-1

41. Copyright (c) by W. H. Freeman and Company 19.1 Heterodimeric tubulin subunits compose the wall of a microtubule Figure 19-2

42. Copyright (c) by W. H. Freeman and Company 19.1 Arrangement of protofilaments in singlet, doublet, and triplet microtubules Figure 19-3

43. Copyright (c) by W. H. Freeman and Company 19.1 Microtubules form a diverse array of both permanent and transient structures Figure 19-4 Microtubule networks

44. Copyright (c) by W. H. Freeman and Company 19.1 Microtubules assemble from organizing centers Figure 19-5

45. Copyright (c) by W. H. Freeman and Company 19.1 The  -tubulin ring complex nucleates polymerization of tubulin subunits Figure 19-8

46. Copyright (c) by W. H. Freeman and Company 19.2 The steps of microtubule assembly Figure 19-11

47. Copyright (c) by W. H. Freeman and Company 19.2 The ends of growing and shortening microtubules appear different Figure 19-12

48. Copyright (c) by W. H. Freeman and Company 19.2 Dynamic instability is an intrinsic property of microtubules Figure 19-13

49. Copyright (c) by W. H. Freeman and Company 19.2 Dynamic instability in vivo Figure 19-14

50. Copyright (c) by W. H. Freeman and Company 19.2 The GTP cap model has been proposed to explain dynamic instability Figure 19-15

51. Copyright (c) by W. H. Freeman and Company 19.2 Assembly MAPs co-localize with microtubules in vivo Figure 19-17 MicrotubulesMAP4 MAP=Microtubule associated proteins

52. Copyright (c) by W. H. Freeman and Company 19.3 Different proteins are transported at different rates along axons Figure 19-19

53. Copyright (c) by W. H. Freeman and Company 19.3 Fast axonal transport occurs along microtubules Figure 19-20

54. Copyright (c) by W. H. Freeman and Company 19.3 Intracellular vesicles and some organelles travel along microtubules Figure 19-22 ER Microtubules

55. Copyright (c) by W. H. Freeman and Company 19.3 The structure of the kinesin microtubule motor protein Figure 19-23

56. Copyright (c) by W. H. Freeman and Company 19.3 Kinesin is a (+) end-directed motor Figure 19-24

57. Copyright (c) by W. H. Freeman and Company 19.3 Microtubule motors: kinesins and dyneins

58. Copyright (c) by W. H. Freeman and Company 19.3 Dynein-associated MBPs tether cargo to microtubules Figure 19-25

59. Copyright (c) by W. H. Freeman and Company 19.3 Multiple motor proteins are associated with membrane vesicles Figure 19-26

60. Copyright (c) by W. H. Freeman and Company 19.4 Cilia and flagella: structure and movement Figure 19-27

61. Copyright (c) by W. H. Freeman and Company 19.4 All eukaryotic cilia and flagella contain bundles of doublet microtubules Figure 19-28

62. Copyright (c) by W. H. Freeman and Company 19.4 Axonemes are connected to basal bodies Figure 19-29

63. Copyright (c) by W. H. Freeman and Company 19.4 Ciliary and flagellar beating are produced by controlled sliding of outer doublet microtubules Figure 19-30

64. Copyright (c) by W. H. Freeman and Company 19.4 Dynein arms generate the sliding forces in axonemes Figure 19-31

65. Copyright (c) by W. H. Freeman and Company 19.4 Axonemal dyneins are multiheaded motor proteins Figure 19-32

66. Copyright (c) by W. H. Freeman and Company 19.5 The stages of mitosis and cytokinesis in an animal cell Figure 19-34 Movimento dos cromossomas

67. Copyright (c) by W. H. Freeman and Company 19.6 Functions and structure of intermediate filaments distinguish them from other cytoskeletal fibers Figure 19-50

68. Copyright (c) by W. H. Freeman and Company 19.6 All IF proteins have a conserved core domain and are organized similarly into filaments Figure 19-51

69. Copyright (c) by W. H. Freeman and Company 19.6 A purified neurofilament Figure 19-52

70. Copyright (c) by W. H. Freeman and Company 19.6 Intermediate filaments are dynamic polymers in the cell Figure 19-53

71. Copyright (c) by W. H. Freeman and Company 19.6 Various proteins cross-link intermediate filaments and connect them to other cell structures Figure 19-54

72. Copyright (c) by W. H. Freeman and Company 19.6 Intermediate filaments are anchored in cell junctions Figure 19-56

73. Copyright (c) by W. H. Freeman and Company 19.6 Desmin and associated proteins stabilize sarcomeres in muscle Figure 19-57