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.|
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FAQs – Fimbriae vs Flagella
Q. Are fimbriae used for motility?
Ans: No. Fimbriae are not used for motility. Generally fimbriae are used for surface attachment.
Q. What is main function of fimbriae function?
Ans: Attachment of surfaces is the main function of fimbriae not motility.