September 21, 2011 Biology 311C Lecture 11 • The cytoskeleton is a network of fibers extending throughout the cytoplasm. • It organizes the cell’s structures and activities, anchoring many organelles. • It is composed of three types of molecular structures: microtubules, microfilaments, and intermediate filaments. • We should compare and contrast: structure of the three types (components, hollow?, size), function (movement?, tension?, compression?), location in cell (nucleus, cytoplasm), motor proteins (kynesin, myosin (interacting with inner filaments), dynein). • The movement of RNA molecules form the nucleus to the cytoplasm is not involved in the cytoplasm in eukaryotic cells. • The structure of microtubules are hollow tubes; wall consists of 13 columns of tubulin molecules. It has a diameter of 25 nm with 15-nm lumen. • Its protein subunits are tubulin, a dimer consisting of alpha tubulin and beta tubulin. • Its main functions include maintenance of cell shape, cell motility, chromosome
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