Question

Dynein "walking" toward the (-) end of MTs causes the cilium or flagellum to bend in one direction. What is responsible for the reciprocal bending in the opposite direction?

1) dynein walking toward the + end of MTs
2) kinesins
3) it is a rebound force generated by the connective hold of the nexin cross-link proteins
4) it is caused by the contraction of microfilaments

Answer 1

The reciprocal bending in the opposite direction of the dynein-induced movement in cilia and flagella is due to the rebound force generated by nexin cross-link proteins. The correct option is 1) dynein walking toward the + end of MTs

Step-by-step explanation:

The reciprocal bending of cilia and flagella in the opposite direction to dynein walking toward the (-) end of microtubules is not due to dynein walking toward the (+) end, nor is it caused by the action of kinesins or the contraction of microfilaments.

Rather, it is a rebound force generated by the connective hold of nexin cross-link proteins. This constrains the microtubule sliding, initially caused by the activity of dynein, and allows for the cilia or flagella to bend back in the opposite direction once the force exerted by dynein is released. The correct option is 1) dynein walking toward the + end of MTs