Final answer:
Myosin movement along actin filaments in muscle contraction is powered by the hydrolysis of ATP, releasing energy for the power stroke. The Sliding Filament Theory describes this as myosin heads 'walking' along the actin, pulling the filaments and shortening the sarcomere.
Step-by-step explanation:
The energy required for myosin movement along actin filaments in muscle contraction is provided by adenosine triphosphate (ATP). Myosin heads form cross-bridges with actin filaments and utilize the energy from ATP to effect conformational changes that enable them to 'walk' along the actin filaments. As ATP is hydrolyzed to adenosine diphosphate (ADP) and an inorganic phosphate, energy is released for the power stroke, which results in muscle contraction. This cellular process occurs in events such as cell division in eukaryotic cells and cytoplasmic streaming in plant cells, as well as in muscle cells where it is responsible for muscle contraction.
Sliding Filament Theory explains the mechanics behind muscle fiber contraction. The theory states that myosin walks along actin filaments, pulling them closer and shortening the sarcomere. This action is driven by allosteric changes in the myosin heads, which are empowered to 'walk' due to the hydrolysis of ATP, indicating a micro-contraction cycle.