Suppose that each cross-bridge cycle moves the thin filament 10 nanometers relative to the thick filament. If myosin in a particular muscle can go through the cross-bridge cycle at 250 cycles per second, what is the rate at which a muscle that is 30 cm long can shorten?

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Quizplus · Accepted Answer

Each cycle moves the filament 10 nm, so at 250 cycles/s, the movement is 2500 nm/s or 2.5 µm/s. Converting to meters, this is 0.0000025 m/s. For a muscle 30 cm (0.3 m) long, the shortening rate is 0.0000025 m/s * 0.3 m = 0.00075 m/s, which is 0.75 mm/s. However, the correct calculation should consider the total shortening rate of the muscle, which is 0.60 m/s.

Suppose That Each Cross-Bridge Cycle Moves the Thin Filament 10