Question

Movements of cilia and flagella occur by

• A. Nexin and 9 + 2 microfilaments.
• B. Dynein arms and 9 + 2 microfilaments.
• C. Dynein arms and 9 + 2 microtubules.
• D. Collagen and 9 + 2 microfilaments.

Answer 1

The correct option is C Dynein arms and 9 + 2 microtubules.

The motion of cilia and flagella results from movement of dynein along microtubules.

Cilia and flagella are motile structures extending from the surface of many protists and certain cells of animals and plants. Eukaryotic cilia and flagella are ensheathed in an extension of plasma membrane, and contain nine fused pairs of microtubules arranged around two central microtubules, called as 9+2 arrangement.

Ciliary and flagellar motion results from the coordinated sliding of outer doublet microtubules relative to their neighbours driven by ATP. The propelling action of cilia and the intracellular transport of organelles all rely on same fundamental mechanism, i.e., splitting of ATP by proteins such as kinesin, myosin and dynein which drives the sliding motion along microtubules. Kinesin and dynein are actually ATP driven molecular engines that move along the microtubular "rails".