Differences between fimbriae and pili

Differences between Fimbriae and Pili 4.35/5 (74)

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Differences between Fimbriae and Pili

Fimbriae and Pili are filamentous structures composed of protein that extend from the surface of a cell and can have many functions.
Fimbriae are found in gram negative as well as gram positive bacteria but are shorter in length as compared to pili. Pili are longer than fimbriae and there are only a few per cell.

Differences between fimbriae and pili

Some of the differences between fimbriae and pili are as follows:

S.N. Characteristics Fimbriae Pili
1 Definition Fimbriae are tiny bristle-like fibers arising from the surface of bacterial cells. Pili are hair like microfibers that are thick tubular structure made up of pilin.
2 Length Shorter than pili Longer than fimbriae.
3 Diameter Thin Thicker than fimbriae.
4 Number No. of fimbriae are 200-400 per cell. No of pili are less 1-10 per cell.
5 Made up of Fimbrillin protein. Pilin protein.
6 Rigidity Less rigid. More rigid than fimbriae.
7 Found in Both gram positive and gram negative bacteria. Only gram negative bacteria.
8 Formation Is governed by bacterial genes in the nucleoid region. Is governed by plasmid genes.
9 Function Responsible for cell to surface attachment. Specialized for attachment i.e. enable the cell to adhere the surfaces of other bacteria. Responsible for bacterial conjugation.

Two basic function of pili. They are gene transfer and attachment.

10 Motility Do not function in active motility. Type IV pili shows twitching type of motility.
11 Receptors No receptors of other. Serve as receptor for certain viruses.
12 Examples Salmonella typhimurium, Shigella dysenteriae.
Shigella dysenteriae uses its fimbriae to attach to the intestine and then produces a toxin that causes diarrhea.
Escherichia coli, Neisseria gonorrhoeae.

Neisseria gonorrhoeae, the cause of gonorrhea, uses pili to attach to the urogenital and cervical epithelium when it causes disease.

Differences between Fimbriae and Pili

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