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Definition
composed of myosin molecules
thicker
one in each layer (in the middle) |
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Definition
formed by the joined ends of thin filaments
zig-zag line |
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Definition
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Definition
composed of actin, troponin, and tropomyosin
thinner
2 of each in a layer |
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Term
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Definition
a small globular protein
each thin filament contains wo strands of this molecule that are twisted together
each molecule contains a binding site for a myosin head on a thick filament |
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Term
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Definition
thick filaments are bundles of this
each molecule is composed of a long shaft, one end of which terminates in two globular heads (like a golf club)
each myosin head has two important binding sites, one for ATP and one for thin filaments |
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Term
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Definition
1. myosin binding sites on the actin molecules are covered in resting fibers
2. the action potential increases Ca2+ from the SR
3. Ca2+ binds troponin. Tropomyosin moves, revealing myosin binding sites
4. cross-bridge forms when myosin head binds actin
5. Power stroke= myosin head pivots moving actin. ADP and P dissociate from the myosin head
6. Myosin head releases actin when a fresh ATP binds
7. Mysoin head binds next actin. The ATP is cleaved to ADP + P; the cycle repeats |
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