1. Dumangcas Durante OdchimarRoa, S.

2. These nonmuscle cells lies just beneath theplasma membrane Arrangementsare less ordered, morelabile, and transient unlike musclecells/tissues. typicallyrestricted to a thin cortexcortex is an active region of the cell,responsible for many cellular processes(e.g. the constriction of a single animal cell into twocells during cell division.) 3. 1) Nucleating proteins2) Monomer-sequestering proteins3) End-blocking (capping) proteins4) Monomer-polymerizing proteins5) Actin filament-depolymerizing proteins6) Cross-linking proteins7) Filament-severing proteins8) Membrane-binding proteins 4. nucleation Nucleatingprotein 5. - prevent polymerizingby isolationMonomer- sequestering proteins 6. - regulate the length of actin filaments bybinding on an end and blocking a loss orgain of subunitsCappingproteins 7. - promote the growth of actin filaments 8. - fragment actin filaments and promote depolymerization at the pointed end. 9. promote the formation of loose networks offilaments promote the bundling of actin filaments intotightly knit, parallel arrays 10. bind to the side of an existing filament andbreak it in two. 11. - Link the actin filaments to the plasmamembrane indirectly, by means ofattachment to a peripheral membraneproteinMembrane- binding proteins 12. Actin Polymerization as a Force-Generating Mechanism Cell Locomotion Cells that Crawl over the Substratum AxonalOutgrowth Changes in Cell Shape during EmbryonicDevelopment 13. Howis the bacterial cell able to induce the formation of actin filaments at a particular site on its surface? Because Listeria contains a surface protein called ActA, it recruits and activates a number of host proteins that work together to direct the process of actin polymerization. (without the participation of myosin motors) 14. Cells that Crawl over the Substratum Aided by lamellipodia, it extend out from thecell as a broad, flattened, veil-like protrusion.Found by examining its leading edge. 15. Scanning electron micrograph of a mouse fibroblastcrawling over the surface of a culture dish. 16. Cells that Crawl over the Substratum Aided by lamellipodia, it extend out from thecell as a broad, flattened, veil-like protrusion.Found by examining its leading edge. With these cells can move or analogically canwalk. 17. shows the protrusion of the leadingedge of the cell in the form of alamellipodium. shows the adhesion of the lamellipodium to the substratum, to grip the substratum.showsthe movement of the bulk of thecell forwardshowsthe rear of the cell has been pulled forward. 18. Cells that Crawl over the Substratum Aided by lamellipodia, it extend out from thecell as a broad, flattened, veil-like protrusion.Found by examining its leading edge. With these cells can move or analogically canwalk. The protrusion of a lamellipodium isassociated with the nucleation andpolymerization of actin filaments and theirassociation with various types of actin-bindingproteins. 19. A proposed mechanismfor the movement of a cell in a directed manner 20. Cells that Crawl over the Substratum Lamellipodial movement is a dynamic process. As actin filament polymerization and branchingcontinue at the very front edge of thelamellipodium, actin filaments are depolymerizingtoward the rear of the lamellipodium. 21. FluorescenceDrawing of a filamentous actinmicrographs of a fish network of the lamellipodiumkeratocyteand the actinmyosininteractions 22. theexperiment of Ross Harrison provided a strong evidence that axons develop by a process of active outgrowth and elongation. Thetip of an elongating axon consists of a growth cone, which resembles a highly motile, crawling fibroblast and contains several types of locomotor protrusions, including a lamellipodium, microspikes, and filopodia. 23. Changes in cell shape are brought about largely by changes in the orientation of cytoskeletal elements within the cells. One of the best examples of this phenomenon is seen in the early stages of the development of the nervous system.