[Campbell Biology P.164] How do dynein motor proteins contribute to the bending movement of ... | Practice Question

How do dynein motor proteins contribute to the bending movement of flagella and motile cilia?

  • A: Dyneins attached to outer microtubule doublets "walk" along adjacent doublets using ATP, causing the microtubules to slide past each other, which leads to bending when sliding is prevented by flexible cross-linking proteins.
  • B: Dyneins generate tension between the outer doublets, pulling them closer together to cause bending.
  • C: Dyneins directly push the central microtubules, causing the entire structure to undulate.
  • D: Dyneins act as flexible cross-linking proteins, allowing the microtubules to slide freely, which results in bending.

Explanation

Dyneins are large motor proteins attached along outer microtubule doublets. They have 'feet' that 'walk' along the microtubule of the adjacent doublet, using ATP. The text explains that if the doublets were not held in place by flexible cross-linking proteins, the dynein action would make them slide past each other. Instead, because sliding is prevented, the movements of the dynein feet cause the microtubules, and thus the entire organelle, to bend.