Final answer:
The proteins responsible for muscle contraction as they slide past one another are actin and myosin, following the sliding filament model of muscle contraction, which is initiated by the presence of calcium ions and ATP.B) actin and myosin
Step-by-step explanation:
The two proteins found in muscle tissue that cause muscle contraction as they slide past one another are actin and myosin. During muscle contraction, the myofilaments of actin and myosin interact in the sarcomeres, the basic functional units of muscle fibers.
Muscle contraction follows the sliding filament model, where the thin actin filaments slide past the thick myosin filaments, creating a contraction as the sarcomere shortens. The presence of calcium ions (Ca++) is critical, as it leads to a conformational change in troponin, moving tropomyosin off the myosin-binding sites on the actin filament, thereby allowing the formation of cross-bridges between myosin heads and actin sites. This action, coupled with the hydrolysis of ATP, provides the energy required for muscle contraction and the subsequent movement of body parts.