Practice question

Sea urchin sperm propulsion depends on highly conserved flagellar axoneme structure composed of nine outer microtubule doublets surrounding central pair with dynein arms and nexin links. Dynein heavy chain is ATPase motor protein that hydrolyzes ATP to slide adjacent doublet microtubules relative to each other, converting chemical energy into mechanical bending motion of flagellum that propels cell forward. Activation by intracellular pH rise stimulates dynein ATPase catalytic activity. Specific mutations or chemical inhibitors of dynein such as vanadate abolish motility while actin, myosin and tubulin alone provide structural tracks but no motor power. Thus dynein-driven microtubule sliding drives flagellar propulsion.