Microorganisms such as the bacteria, euglena, amoeba, fungi, exhibits different kinds of locomotion, for instance, amoeba move by protrusions of its pseudopodium. On the other hand, bacteria move by beating of its cilia or flagella in their environment.

Lopotrichous bacteria,having multiple flagella on one side of the cell

Therefore, Cilia and flagella are whip like structures used for locomotion by bacteria. There is a difference between the two structures.

Flagella are slender and long whip like structures of about 100 to 200mm in length, they are so tiny that they cannot be seen with bright field microscope and are only observed when stained with special staining procedure that increases their thickness.

Apart from movement, flagella also function as sensory structure that is sensitive to chemicals and temperature of the external environment of the cell.

Apart from Prokaryotic (single cell), eukaryotic also have flagella, though, they differ in their protein composition, structure and mechanism of propulsion.

Bacteria species differs in their patterns of flagella arrangement.

Monotrichous: This is when the microorganism has a single flagella located at one end of the cell, this arrangement gives it the name Polar flagellum. An example is Vibro cholerae

Amphitrichous:This is when the bacteria has two flagella,  on each ends, e.g, Alkaligens faecalis

Lophotrichous:This is when bacterium has multiple flagella attached to one or both sides of the cell. Example, Spirillum.

Peritrichous:This is when the flagellum is spread all over the whole surface of a bacterium.

Flagella Ultra Structure

Filament: This is the most visible part and extends from the cell surface to the tip.

Basal body: It is embedded in the cell

Hook: The hook is the short curve segment that joins the flagella to the basal body and act as a flexible coupling

Also, there is a different in the kind of locomotion exhibited by both structures, flagella moves in an undulating manner and generates planar or helical waves originating at either the base or tip, when the wave move from base to tip, the cell is propelled along.

Some flagella develop lateral hairs known as Flimmer filaments. These filaments, changes the action of flagella such that a wave moving down the filament towards the tip pulls the cell along, this kind of appendage is known as Tinsel Flagella.

Other types of flagellated bacteria are,

Helicobacteria pylori: H. pylori is the ulcer causing bacterium, microscopic details shows it has four flagella each on both sides of the cell (Lopotrichous), this enables the organism to move through mucous lining to reach the stomach.


Cilia, are short structures of about 5-20mm only, they are microscope.

The structure beats in two phases to cause movement in bacteria, the first is known as effective stroke, during which it strokes through the surrounding fluid like an Oar, thereby propelling the organism along in the water.  The second is the recovery, the cilia bend along its length while it pulls forward in preparation for the next effective stroke.

This bends is as a result of adjacent microtubule doublet sliding through one another while maintaining their individual length. The double arms are made up of protein dynein.

A ciliated organism coordinates the beats so that some of the cilia are in recovery phase while others are carrying out the effective stroke; this process allows the organism to move through the water.

Cilia and flagella beat at a rate of 10 – 40strokes or wave per second and propel the organism very quickly.  ATP provides the energy that powers the movement of this organelle.

There is no difference in the ultra structures of flagella and cilia, both are very much alike, both are membrane bound cylinders.

Located in the matrix of the organelle, is the axoneme, consisting of nine pairs of microtubules doublets arranged in a circle around two central tubules. This is known as the 9 + 2 pattern of microtubules.

There is a basal body embedded in the Cytoplasm  at the base of each cilia and flagella. The basal body is a short cylinder with nine microtubules triplets around its periphery (9 + 0) pattern and is separated from the rest of the organelle by a basal plate.

Basal body coordinates the formation of these organelles.





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