Final answer:
The myosin heads at opposite ends of a myosin filament can engage in the cross-bridge cycle, leading to the shortening of sarcomeres and muscle contraction.
Step-by-step explanation:
Because they are bipolar, the myosin heads at the opposite ends of a myosin filament have the ability to engage in actions that lead to muscle contraction via the cross-bridge cycle.
This cycle consists of myosin heads with attaches ADP and Pi binding to actin binding sites, pulling the actin filaments with a power stroke and releasing ADP and Pi. Subsequently, ATP attaches to the myosin head, leading to its detachment from actin, and upon ATP hydrolysis, the myosin head is re-cocked into a high-energy state, allowing the cycle to repeat.
This cyclical interaction is what gathers the actin filaments from either side towards the center, drawing the Z-lines closer together and shortening the sarcomeres, ultimately resulting in muscle contraction.