Question

muscles contract when the head of a(n) protein filament binds to an active site on a(n) filament. the two proteins release and rebind multiple times as they one another, pulling the s together and contracting the where they are located. sarcomere slide past myosin myofibril entangle with actin z disc

Explanation:

Muscle contraction involves myosin (thick filament) binding to actin (thin filament). They slide past each other, pulling Z - discs (which mark the boundaries of a sarcomere) closer, contracting the sarcomere (the basic unit of muscle contraction within a myofibril).

Answer:

1. myosin
2. actin
3. slide past
4. Z - discs
5. sarcomere