Kingdom Monera - Pili & Fimbriae

Description:

Pili and fimbriae are the hair like outgrowths on the bacterial cell surface. They are not involved in locomotion. Pili and fimbriae differ from each other both structurally and functionally.

Pili

• Pili are long, fewer and thicker tubular outgrowths.
• They develop in response to F + or fertility factor in gram negative bacteria.
• They are made up of pilin protein.
• A donor bacterial cell having fertility factor develops 1-4 pili.
• They are helpful in attaching to recipient cell and forming of the conjugation tube.

Fimbriae

• Small-bristle like fibres sprouting from cell surface in large numbers.
• 300-400 fimbriae are present per cell.
• They are involved in attaching bacteria to solid surface.
• Some causes agglutination of RBC.
• They also help in mutual clinging of bacteria.