Ch 50 - Ch50(P:11051108 , cytoskeleton. ; ,responsibleformo

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Ch 50 (P: 1105-1108) Muscle cell function relies on microfilaments, which are the actin components of  cytoskeleton. Microfilament movement powered by chemical energy  brings about contraction; muscle extension occurs only passively.  Skeletal muscle  is attached to the bones, responsible for movement, and  characterized by hierarchy of smaller and smaller units. Consists of bundle  of long fibers (single cell w/ multiply nuclei) parallel to the length of the  muscle.  muscle fiber contains bundle of smaller  myofibrils  arranged  longitudinally. Myofibrilis are composed of:  thin filaments  - consist of 2 strands  of actin and 2 strands of a regulaotry protein coiled around one another and  attached at the Z lines and project toward the center of the sacromere;  and thick  filaments  - staggered (arrange in zigzag pattern) arrays of myosin molecules,  attached at the M lines centered in the sacromere.   also called  striated muscle  bc arrangments of filament creates a patterns of  light and dark bands. Each repeating unit is  sarcomere  - the basic  contractile unit of the muscle; a muscle fiber at rest, in the edge contains  thin muscle and center contains thick muscles<This arrangement is the  key to how the sacromere and whole muscles contracts Sliding-filament model : during muscle contraction, neither thin filaments nor 
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This note was uploaded on 01/30/2011 for the course BIOL 303 taught by Professor Birchard during the Spring '08 term at George Mason.

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Ch 50 - Ch50(P:11051108 , cytoskeleton. ; ,responsibleformo

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