Microfilaments are solid rods about 7 nm in diameter

Microfilaments are solid rods about 7 nm in diameter -...

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Microfilaments  are solid rods about 7 nm in diameter. Each microfilament is built as a twisted double chain of actin subunits. Microfilaments can form structural networks due to their ability to branch. The structural role of microfilaments in the cytoskeleton is to bear tension, resisting pulling  forces within the cell. They form a three-dimensional network just inside the plasma membrane to help support the  cell’s shape, giving the cell cortex the semisolid consistency of a gel. Microfilaments are important in cell motility, especially as part of the contractile apparatus of  muscle cells. In muscle cells, thousands of actin filaments are arranged parallel to one another. Thicker filaments composed of  myosin  interdigitate with the thinner actin fibers. Myosin molecules act as motor proteins, walking along the actin filaments to shorten the  cell. In other cells, actin-myosin aggregates are less organized but still cause localized contraction.
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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