- Most motile bacteria move around using flagella (s. flagellum).
- Filamentous locomotor appendages extending beyond the membrane and cell wall.
- They are Thin, rigid structures, about 20 nm long and up to 15-20 meters long.
- So thin that they can be directly observed with a light field microscope, but they need to be coloured with special methods designed to increase the thickness.
- Fimbriae are filamentous structures composed of protein that extend from the surface of a cell and can have many functions.
- Fimbriae are short, thin, hair-like performances that are thinner than flagella and should not participate in the movement.
- A cell that can be covered with up to 1000 fimbriae.
- They are only visible under an electron microscope due to their small size.
Similarities between Flagella and Fimbriae
- Flagella and Fimbriae both are filamentous in structure.
- In both Gram positive and Gram negative Flagella or Fimbriae may be present.
- Both are present in cell surface of bacteria.
- Flagella as well as Fimbriae both are made up of Proteins but ingredient may varies.
Difference between Fimbriae and Flagella
|Structure||Bristle-like filamentous structure on surface of some bacteria.||Whip-like filamentous structure on surface of some bacteria.|
|Origin||They are external in origin.||They are internal in origin.|
|Originated From||Fimbriae are originated from the cell wall.||Flagella are originated from membrane of cytoplasm.|
|Helical Nature||Fimbriae are non-helical in nature.||Flagella are helical in nature.|
|Straight Nature||Fimbriae are straight.||Flagella are not straight.|
|Made up of which protein||Fimbriae are made up of specific protein called fimbrilin or pilin protein.||Flagella are made up of specific protein called flagellin protein.|
|Rigidity||Fimbriae are less rigid than flagella.||Flagella are more rigid than fimbriae.|
|Function||Attachment of surfaces is the main function of fimbriae.||Locomotion is the main function of flagella.|
|Role in motility||They do not have any role in motility.||They have main role in motility.|
|Role in surface attachment||Fimbriae have main role in surface attachment.||Flagella do not take part in surface attachment.|
|Diameter||Fimbriae are thin in diameter as compare to flagella.||Flagella are thick in diameter as compare to Fimbriae.|
|Length||They are shorter in length than flagella.||They are longer in length as compared to fimbriae.|
|Range of Length||Fimbriae may varies in length from 0.03 to 0.14 μm.||Flagella may varies in length from 15 to 20 μm.|
FAQs – Fimbriae vs Flagella
1. Are fimbriae used for motility?
Ans: No. Fimbriae are not used for motility. Generally fimbriae are used for surface attachment.
2. What is main function of fimbriae function?
Ans: Attachment of surfaces is the main function of fimbriae not motility.