Flagella Flagella are necessary for the active movement of bacterial cells and protozoa. Flagella are single, whip-like structures that propel an organism through an aquatic environment. They use undulatory motions, where the waves of motion start at the base of the flagellum. The size, the volume of the medium, the length, position and width of the flagella on the organism determine the direction and speed propulsion of the cell. There are three different types of flagella movement. They are either planar, oarlike beating, or three dimensional waves. In the three dimensional wave movement, the flagella whips back and forth. As...
been a great deal of research done on them. Hancock made the first theoretical breakthrough in the mid-50's, although cilia have been known about for 250 years.

Both flagella and cilia move because of a set of microtubles which contain an inner cylindrical body known as the axoneme and an outer membrane. The membrane of the flagellum or cilia contain mastigonemes, tiny scales or hairs on the surface, which increase propulsive force.

Flagella and cilia both are important in our everyday lives. They are in many living organisms. They are similar in structure, with only a few minor differences.