Practice question

Amoeboid movement represents actin-mediated cell crawling observed in Amoeba proteus, entamoebae and slime molds. Polymerization of G-actin into F-actin filaments at leading edge pushes plasma membrane forward, forming lobose or filose pseudopodia filled with endoplasm and ectoplasm. Myosin II contraction at posterior retracts cell body, coupled with sol-gel transitions of cytoplasm. This mechanism enables phagocytosis and substrate exploration without cilia or flagella, distinguishing true pseudopodial locomotion from axonemal-based systems driven by dynein-microtubule sliding, allowing directional chemotaxis toward prey. This receptor-mediated actin remodeling allows rapid engulfment of bacteria, algae and detritus particles essential for heterotrophic protists.