Final answer:
When a myosin II filament is placed between two antiparallel actin filaments, the myosin heads attach to the actin and form cross-bridges, causing the filaments to slide past each other and the muscle to contract.
Step-by-step explanation:
When a myosin II filament is placed between two antiparallel actin filaments, the myosin heads attach to the actin and form cross-bridges. This allows the myosin filaments to pull on the actin filaments, causing them to slide past each other. As a result, the sarcomere shortens and the muscle contracts.
Myosin II filament interacts with antiparallel actin filaments to facilitate muscle contraction through the cross-bridge cycle and power stroke, as explained by the sliding filament model.
When a myosin II filament is placed between two antiparallel actin filaments, it can interact with the actin to facilitate contraction, as per the sliding filament model of muscle contraction. In this model, the myosin filament pulls the actin filaments toward each other by utilizing the energy from adenosine triphosphate (ATP), through a series of steps known as the cross-bridge cycle. Initially, the myosin heads attach to the actin binding sites forming a cross-bridge, then, as ATP is converted to ADP and inorganic phosphate (Pi), the myosin heads pull the actin filaments approximately 10 nm toward the M line during the power stroke. This results in the sliding of the actin filaments past the myosin, shortening the sarcomere, and thus leading to muscle contraction.