They are hair-like outgrowths of the cell membrane.
Cilia are small structures which work like oars, causing the movement of either the cell or the surrounding fluid.
Flagella are comparatively longer and responsible for cell movement.
Flagella of prokaryotic bacteria and eukaryotes are structurally different.
Cilium and flagellum are covered with plasma membrane. Their core (axoneme) possesses a number of microtubules running parallel to the long axis.
The axoneme usually has 9 pairs of doublets of radially arranged peripheralmicrotubules, and a pair of centrally located microtubules. This is known as 9+2 array.
The central tubules are connected by bridges and are also enclosed by a central sheath, which is connected to one of the tubules of each peripheral doublet by a radial spoke. Thus, there are nine radial spokes. The peripheral doublets are also interconnected by linkers.
Both the cilium and flagellum emerge from centriole-like structure called the basal bodies.
