Biology 332 - Protistology Term 2 - 2002-2003

Flagellar Motion in Paramecium

The flagellar beat pattern in Paramecium is divided into a powerstroke during which the flagellum is held stiff and moves quickly downward in a plane perpendicular to the surface of the cell, and a return stroke in which the flagellum is less rigid and returns out of the plant of the power stroke. This animation shows the pattern of movement with the powerstroke shown in a darker color than the return stroke.

cilium.gif (330780 bytes) This animation shows a lateral view of a flagellum (above) and a vertical view (below) of the same flagellum. The numbers refer to the position of the flagellum in successive frames of a high-speed video. Notice that the flagellar beat pattern is conical. During the power stroke (green), directed to the right, the flagellum is held rather stiffly as it moves rapidly downward in  a single plane. During the return stroke (red), the distal portion of the flagellum drags as it moves laterally and upward, back to the starting position to begin a new power stroke. Notice that the first half of the return stroke is in a plane nearly perpendicular to the power stroke. Data from Machemer et al.

As you look at this animation, think about that has to be occurring to control the activity of the dynein motor proteins in the flagellum to produce this pattern.