Extracellular structures in Bacteria MCQ - Practice Questions with Answers

Extracellular structures in bacteria are pili, fimbriae and flagella
Pili and Fimbriae

• Pili and fimbriae are bacterial appendages that are not involved in locomotion.
• Pili are long, thick, tubular outgrowths that help in attachment of donor cell to a recipient cell and form conjugation tube.
• Pili consist of a protein called pillin.
• Fimbriae are short and narrower outgrowth that take part in adhesion of bacteria to solid surfaces.

 Flagellum

• An organ of motility in bacteria.
• Arise from basal granule called blepharoplast.
• Flagella have 3 parts i.e. basal body, hook and filament.
• The basal body is a rod-like structure having ring-like swellings and embedded in the cell envelope. There are two pairs of rings L and P (in the cell wall)  and S and M (in Cell membrane).
• The hook is curved structure attaching the basal body to the filament.
• The filament is a long tubular structure composed of the protein flagellin.
• Bacterial flagella perform rotation type movement that brings backwards pushing of the water.