国外大学细胞生物学课件 英文课件8.ppt

W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. 1 Lecture 8 Microtubules and Intermediate filaments 1. Dynein-mediated mechanism of cell swimming 2. Intermediate filaments ? Lamins and their role in anization 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. 2 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. 3 ? 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. 4 Flagella-based cell motility Cilia ? short W2011 - D103 Cell Biology – lecture 8 ? Suetterlin and MacGregor - all rights reserved. 5 Same anization 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. 6 Intermediate filaments ? nm in diameter ? biochemically heterogeneous: at least 70 genes in mammalian cells ? tissue specific ? found mainly in anisms ? main function: Impart physical strength to cells and tissues Keratin lamin7 ? not conserved: not found in all eukaryotes, not found in al