3HH3 module 1 lecture 2-post

3HH3 module 1 lecture 2-post - Microtubules are dynamic...

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Microtubules are dynamic structures. http://www.youtube.com/watch? Nucleation of microtubules Polymerization or elongation Dynamic instability: catastrophe and rescue
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Bio 3HH3 2010 2 Microtubules: Nucleation While α- and β-tubulin are the building blocks of microtubules, another type of tubulin, γ -tubulin, is involved in nucleation of Mts γ-tubulin is present in much smaller amount in cells compared to α- and β- tubulin
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Bio 3HH3 2010 3 γ -tubulin and other associated proteins bind at the minus end of the tubulin and serve as a template for nucleation acts as a cap of the minus end while microtubule growth continues away from the MTOC in the plus direction. Figure 16-29 Molecular Biology of the Cell (© Garland Science 2008) γ -tubulin ring complex, γ -TuRC
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http://www.msg.ucsf.edu/agard/research/centrosome. html
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Bio 3HH3 2010 5 Microtubule-organizing centre (MTOC) This is a specific location inside the cell where microtubule nucleation is initiated. In animal cells, MTOC is called a centrosome and is located near the nucleus. Figure 16-30 Molecular Biology of the Cell (© Garland Science 2008)
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Bio 3HH3 2010 6 The centrosome (MTOC) Centrioles: two cylindrical structures located inside the centrosome that organize the centrosome matrix (pericentriolar material) ensuring its duplication during cell cycle.
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Bio 3HH3 2010 7 During cell cycle, MTs undergo highly ordered reorganization to form bipolar spindles This led to the notion of an organizer that regulates such activities: microtubule organizing centre or MTOC Early electron microscopy studies revealed two visible structures that appeared as important MTOCs. centrosome (in animal cells) spindle polar bodies (in yeast)
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Bio 3HH3 2010 8 Microtubule filaments are oriented with the minus end at the MTOC and the plus end extending away from it. Nucleating microtubules for formation of the mitotic spindle: Pericentriolar material (PCM): surrounds the centriole pair and contains l TuRC Two barrel-shaped cylinders inside a centrosome
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Centrioles: The wall of each centriole cylinder is made of nine interconnected triplet microtubules. EM of centriole
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Bio 3HH3 2010 10 G-tubulin complexes at different types of MTOCs Models for the organization g-tubulin complexes in MTOCs a) centrioles b) surface of membranes with similar matric to (a) c) membrane surface d) g-tubulin on lateral surface of microtubules f) free in cytoplasm
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Bio 3HH3 2010 11 Luders & Stearns, Nature Reviews MCB 2007, 8, 161-167
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http://www.molbio.uoregon.edu/~bowermanlab/movies.html
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This note was uploaded on 04/12/2011 for the course BIOL 3HH3 taught by Professor Mccelland&dej during the Winter '11 term at McMaster University.

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3HH3 module 1 lecture 2-post - Microtubules are dynamic...

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