How do cilia and flagella bend?

Answer 1

you should refer to a sliding microtubule model. in this model, there is a "9+2" structure or pattern, along with spokes, motor proteins and a basal body. the spokes connect to the 2 microtubules in the center and the motor protein, dynein, connects the 9 pairs to each other. dynein "walks" one microtubule pair relative to the other. if they weren't fixed in place at either end, they would move past each other. they are fixed at one end by attachment to the basal body, which is attacked just inside the plasma membrane. therefore the walking motion pulls the microtubule pairs over (while spokes contribute to the lack of free movement). keep in mind that dynein requires energy. it binds, releases and moves, binds, releases and moves. (think of a cat climbing a tree.)