Final answer:
Actin filaments can be altered by myosin and ATP binding, which facilitates muscle contraction and cell movement. They provide structural support to cells and have a dynamic nature, essential for processes like cell division. Their polarity allows for rapid assembly and disassembly, enabling cellular reorganization.
Step-by-step explanation:
Actin filaments, or microfilaments, can be altered by interaction with motor proteins like myosin, and by binding and hydrolysis of ATP. These actin filaments play a crucial role in cellular processes such as muscle contraction, cell division, and cell motility. When myosin binds to actin in the presence of ATP, it allows for muscle contraction through the sliding filament model. In addition to their contractile capabilities, actin filaments contribute to the cell's structural integrity, helping it to maintain shape and perform various dynamic activities such as amoeboid movement and cytoplasmic streaming in plant cells.
Actin filament polymerization and depolymerization are dynamic, allowing cells to quickly change shape and move. This is essential for processes like cell division, where actin filaments form a contractile ring during cytokinesis. The structure of actin filaments also demonstrates polarity, meaning they have a 'plus' end, where new actin monomers are added, and a 'minus' end, where disassembly can occur, enabling dynamic reorganization within the cell.