Final answer:
Sarcodina move by extending pseudopodia due to the forward flow of actin filaments, followed by a process of gel-sol cycling, allowing the cell to create forward locomotion.
Step-by-step explanation:
Sarcodina, such as amoebae, move using pseudopodia. These are temporary extensions of the cell that are formed when soluble actin filaments flow forward into the extending pseudopodium. This process is followed by gel-sol cycling of the actin filaments which results in cell motility. As the cytoplasm extends outward, forming a pseudopodium, the remaining portion of the cell's contents flows forward to fill the void, thus creating the movement.
Beyond amoeboid movement, microfilaments have roles in other cellular processes, such as cytoplasmic streaming, cleavage during cell division, and muscle movement. This is due to their ability to polymerize and depolymerize in response to cellular signals, and interact with molecular motors like myosin.