Question

Explain the structure and function of cilia, flagella, and pseudopodia

Answer 1

All three are related in terms of being forms of cellular motility and employing protein structures in order to accomplish their task.

Pseudopods are extensions of cell membranes, made using cytoproteins. Amoeba and human macrophages move by means of pseudopods. The mechanism of creating pseudopods is too long and complex, but basically proteins inside the cell contract, creating extensions of the membrane which are then used as traction points to pull the rest of the cell in that direction.

Cilia and flagella are more closely related, as they are both like hairy extensions from the cell membranes.

However Cilia are much shorter and are arranged in multiple groups, working together in coordinated manner to create movement along the cell membrane (kind of like the legs of a centipede). This movement could either be to propel the cell forward (as with paramecia) or move things past the cell (as with the cilia in the human respiratory system).

Flagella are much bigger whip-like extensions that require a lot of energy to produce a great deal of propulsion. Their movement is both rotary and serpentine and they are what drive sperm cells forward.