ppt课件-国外大学细胞生物学ppt课件-英文8.bioy.ppt

W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. * Lecture 8 Microtubules and Intermediate filaments 1. Dynein-mediated mechanism of cell swimming 2. Intermediate filaments Lamins and their role in the organization of the nucleus Keratins and their role in tissue maintenance The movement of a eukaryotic cell W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. * 1. crawling (development, infection, repair) ? actin-dependent 2. swimming (sperm, protozoa) powered by a flagellum - MT/dynein-dependent movement Note: bacteria also contain a flagellum, which is, however, structurally and functionally very different! The mammalian flagellum W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. * 9 doublet microtubule that surround a central pair of singlet MT (axoneme can be very long: 10-200 μm) MTs are cross-linked to each other found in sperm and many protozoa W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. * Flagella-based cell motility Cilia short W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. * Same overall organization as flagella, but shorter 1. Multiple motile cilia Beat in synchrony to move fluid over surface (dynein dependent) Found in many epithelial cells (eg respiratory tract) 2. Single non-motile primary cilium no dynein site of signal transduction ? contains many signaling molecules Defects cause ciliopathies (eg polycystic kidney disease) W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. * Intermediate filaments approx.10 nm in diameter biochemically heterogeneous: at least 70 genes in mammalian cells tissue specific found mainly in multicellular organisms main function: Impart physical strength to cells and tissues Keratin l