Structure and Function of Bacterial Flagella

Flagella singular: flagellum are long, thin, whip-like structures that are attached to a bacterial cell that allows the bacteria for movement.

Flagellar Function in Bacteria

Function of Flagella in Bacteria


They helps in movement (locomotion) of bacteria from one place to another.

Structure of Flagella in Bacteria

Composed of three structures in bacteria.

Gram Positive Bacteria

                   Gram Negative Bacteria
In gram positive bacteria two rings are present. S and M. While in gram negative bacteria four rings are present. L, P, S and M.
Flagella are less common in this type of bacteria. More common in gram negative bacteria.
Structure of Flagella

Structure of Flagella

  1. The basal body is the first part, which is composed of rings and rods.
  2. The second part is Hook. It is proteinaceous in nature.
  3. The third part is filament or shaft. The filament is composed of hollow cylindrical structure that is hollow from inner side and wall around is composed of 8 rows of flagellin protein.

Difference between Prokaryotic and Eukaryotic

Prokaryotic Flagellum

                   Eukaryotic Flagellum
Made up of flagellin protein Made up of tubulin protein.
Filament contains one hollow cylinder and this is known as monofibril. Prokaryotic flagella composed of 8 flagellum protein rows. Filament contains several hollow cylinders in the arrangement of 9+2 microtubules.
Energy for flagellal locomotion is provided by other than ATP bioenergy molecules. Energy source is provided by ATP.
Membrane around flagella is absent. Membrane is present.
Flagellar Movement takes place at 360o and the movement is called Rotatory movement. Flagellar Movement takes place at 180o and the movement is called Flapping movement.
Difference Between Prokaryotic and Eukaryotic Flagella

Prokaryotic and Eukaryotic Flagellum

Different Types of Trichous Bacteria

Following are the types of Trichous Bacteria. The arrangement is divided on the basis of their position and number:

Types of Flagellar Arrangement

  1. Monotrichous: Bacteria containing one flagella at either one pole is known as monotrichous.
  2. Amphitrichous: Bacteria containing two flagella at both sides/poles is known as Amphitrichous.
  3. Cephalotrichous: Bacteria containing group of flagella at either one pole is known as Cephalotrichous.
  4. Lophotrichous: Bacteria containing group of flagella at both sides/pole is known as Lophotrichous.
  5. Peritrichous: Bacterial surrounded by flagella is known as Peritrichous.

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