Ani Phys 10-04-07

Ani Phys 10-04-07 - Ani Phys 10-04-07 Striatal muscle...

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Ani Phys 10-04-07 Striatal muscle Differences between arthropods and vertebrates on how they work to do contractions and a bit of smooth muscle maybe Getting us to the point where actin and myosin bind Action potential comes in and releases acetylcholine and causes a motor end plate potential??? T tubules… Release of calcium from the sarcomere… all from last Thursday Calcium binds to troponin which uncovers tropomyosin, which is this kind of bluish-redish stripe here causing actin and myosin to bind. Action potential causes release of calcium allowing actin and myosin to bind. Talked about thick filament – myosin Classified as molecular motor, pg. 17 Specifically known as myosin-2 molecules Found in smooth and Striatal muscle Striatal muscle Consists of 2 heads Long filament… The tail is important because how myosin molecules self assemble – interaction and bonding of aa within the tail… look at picture on handout Notice that myosin heads are arranged in a very non-random manner; the distance between the heads is always constant No enzymes required The arrangement is such that they’re organized so that there’s a specific distance between them… you’ll see here a 2D image even though it’s a 3D molecule… myosin molecules are sticking out and above each one you’ll see a thin filament, which, of course is the actin What’s unique about the myosin head is what I call the ‘roommate hypothesis’ A small apartment, comfy for one person and no more… If one roommate is there the other has to wait in the hall Same is true of the myosin head only one molecule can bind to the myosin head at any one time When we talked about 2 types of molecules binding to the myosin 1. actin 2. ADP
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thus, the myosin head has 2 binding sites only one of these molecules can bind to the myosin head at one time, so the other has to wait. This is an essential component of the sliding filament theory of the muscle contraction balls are actin, the heads are myosin if the binding site of actin becomes unconvered due to step 3, actin and myosin will bind the binding of these 2 removes ADP ADP was once ATP and that high energy phosphate is transferred to the neck of myosin, causing the neck to bend It bends, swivels, whatever you wanna call it Because the 2 are tightly bound, it drags poor helpless actin with it thought that amount of movement/dragging of poor actin is somewhere between 12-16 nanometers depending on the cell type/animal, etc… When the myosin head is at bent configuration, its affinity for a
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This note was uploaded on 04/15/2008 for the course BIOL 482 taught by Professor Cohen during the Fall '07 term at CSU Northridge.

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Ani Phys 10-04-07 - Ani Phys 10-04-07 Striatal muscle...

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