15-19 Sliding Filament Theory (Cambridge AS A Level Biology, 9700)

Steps in the Sliding Filament Theory:

– Calcium ions bind to troponin on the actin filament
– causes the tropomyosin shape to change, exposing the actin filaments to the myosin head
– myosin head attaches to the actin filament
– Myosin head tilts back towards the M-line, pulling the actin filament in the process
– Sarcomere distance reduces
– Myosin head hydrolyzes ATP into ADP + Pi, and releases the molecules.
– Myosin head detaches from the actin filament
– New ATP molecule reattaches to the myosin head, and restarts the whole process