Cell_class5_Bachelor_sent.pdf - University of Science and Technology Hanoi LECTURE CELLULAR BIOLOGY Lecturer Thao Thi Do PhD Laboratory for Bioassay

Cell_class5_Bachelor_sent.pdf - University of Science and...

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CELLULAR BIOLOGY LECTURE University of Science and Technology Hanoi Lecturer: Thao Thi Do PhD. Laboratory for Bioassay INSTITUTE OF BIOTECHNOLOGY VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY
Cell Movement Cell movement: Internal: cytoplasmic streaming External: motility. Internal movements (organelles): by actin filaments and other components of the cytoskeleton. The cytoskeleton: network of filaments and tubules; extends from the nucleus to the plasma membrane.
Internal Cell Movement Actin filaments: long, thin, polar fibers (7 nm in diameter). An actin filament: consists of two chains of globular actin monomers twisted to form a helix. Actin filaments of intestinal cells act to shorten the cell and thus to pull it out of the intestinal lumen. In plant cells, actin filaments form tracts along which chloroplasts circulate.
Internal Cell Movement Actin filaments move by interacting with myosin. (Myosins: a family of ATP-dependent motor proteins ). Motor proteins: are a class of molecular motors ; powered by the hydrolysis of ATP ; convert chemical energy into mechanical work
Intermediate filaments: 8- 11nm in diameter. The intermediate fibers: rope-like assemblies of fibrous polypeptides. Support the nuclear envelope, plasma membrane, form cell-to-cell junctions.
Cells can move by specialized structures: cilia or flagella Cilia: tiny hairs along the outside membrane; push the cell along Flagella: much larger hairs, propel cell back External Cell Movement and forth. Both cilia and flagella: composed of microtubules.
External Cell Movement Cilia: short, numerous, hairlike projections (move in an undulating fashion) Flagella: longer, fewer in number, projections that move in whip-like fashion (sperm cells). ° Cilia and flagella move: microtubules slide past one another, structures same arrangement as centrioles. ° Flagella works as whips pulling ( Chlamydomonas ) or pushing (dinoflagellates ) the organism through the water.

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