* Cilia are short, hair-like projections that beat in a coordinated, wave-like motion. They are found in large numbers on the surface of some cells, such as those lining the respiratory tract, where they help to move mucus and debris.
* Flagella are longer, whip-like structures that usually occur singly or in pairs. They move in a propeller-like fashion, propelling the cell forward. A classic example is the sperm cell, which uses its single flagellum to swim towards the egg.
Both cilia and flagella are made up of microtubules, which are protein filaments that provide structure and support. They are powered by the motor protein dynein, which uses ATP to generate movement.
