L7 Cilia, Flagella, and Mitosis PDF

BS31004 Cell Shape and Movement: Cilia, Flagella & Mitosis L7 : Microtubule structure and function. Alan Prescott [email protected]  Flagella propel cells Cilia move material across through liquid the surface of cells Sperm and Chlamydomonas C...

BS31004 Cell Shape and Movement: Cilia, Flagella & Mitosis L7 : Microtubule structure and function. Alan Prescott [email protected]  Flagella propel cells Cilia move material across through liquid the surface of cells Sperm and Chlamydomonas Ciliated epithelium Figure 16-80 Molecular Biology of the Cell (© Garland Science 2008) Cross section of a Cilium Trypsinized Axoneme Figure 16-83 Molecular Biology of the Cell (© Garland Science 2008) Figure 16-82a Molecular Biology of the Cell (© Garland Science 2008) Figure 16-64 Molecular Biology of the Cell (© Garland Science 2008) Intraflagellar transport. Many interphase cells contain a non-motile primary cilium.  Centrioles can nucleate primary cilium or spindle MT  Basal bodies Figure 16-84a Molecular Biology of the Cell (© Garland Science 2008) Cross-section of a CENTRIOLE Cr Cyclin Dependent Kinase Cell cycle Mitosis in an animal cell Figure 16-85c Molecular Biology of the Cell (© Garland Science 2008) The stages of mitosis. Figure 16-31a Molecular Biology of the Cell (© Garland Science 2008) Relation of centrosome duplication to the cell cycle. Figure 16-31b Molecular Biology of the Cell (© Garland Science 2008) Figure 16-85a Molecular Biology of the Cell (© Garland Science 2008) Mitotic spindles have three distinct classes of microtubules. Dynamic microtubules from both centrosomes Microtubule dynamics are enhanced during mitosis MT are nucleated at both the centrosome and the sides of other MT  Microtubule Organising Centres Duplicate and Move to Opposite Poles DNA Condensation into Chromosomes Nuclear Envelope Break Down  Kinetochore microtubules To spindle To spindle pole 2 pole 1  Kinetochore side-on microtubule capture Figure 17-38 Molecular Biology of the Cell (© Garland Science 2008) Chromosome capture and congression in prometaphase.  Equal tension must be applied to each side of the kinetochore before chromatid separation can proceed Figure 17-39 Molecular Biology of the Cell (© Garland Science 2008) Microtubules Attach to Kinetochores  Spindle checkpoint proteins and cancers mutated in 45% of gastric cancers, underexpressed in 50% of hepatoma cell lines Mutated in premature chromatid separation Mad 2 Haploinsufficiency increases cancer frequency in mice (PCS syndrome) and mosaic variegated aneuploidy Mad 1 (MVA) Increased tumor predisposition and aging in mice with reduced level of BubR1 BubR1 Defective in Bra2-/- mouse thymic lymphomas and in some human leukemia and lymphomas Aneuploidy, but not tumour (cell lines and tumours) predisposition in Bub3+/- mice Bub3 mutations are not frequent in other tumours kinetochore  Microtubule motors - spindle elongation & chromatid movement Figure 17-30 Molecular Biology of the Cell (© Garland Science 2008) Figure 17-37 Molecular Biology of the Cell (© Garland Science 2008)  The kinetochore maintains attachment to the microtubules whilst allowing for both MT growth and shrinkage Figure 17-40 Molecular Biology of the Cell (© Garland Science 2008) Spindle elongation during Anaphase B is essential for chromosome separation Chromosome movement and spindle pole separation in anaphase. Cytokinesis Cytokinesis Cytokinesis is driven by actin based myosin contraction Actin Myosin  Organelle Inheritance Mitochrondria Bundled Actin Filaments Organelles segregate along cytoskeletal filaments to ensure both daughter cells Inherit all the organelles they need. Some organelles first split by fission. Separation of Sister Chromatids Chromosomal instability