🦠microbiology review

F pilus

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

An F pilus, or sex pilus, is a hair-like appendage found on the surface of many bacteria that facilitates the transfer of DNA between cells during bacterial conjugation. It is primarily composed of the protein pilin and encoded by the F (fertility) plasmid.

5 Must Know Facts For Your Next Test

  1. The F pilus mediates the process of bacterial conjugation by connecting a donor cell to a recipient cell.
  2. It is encoded by genes located on the F plasmid (fertility factor).
  3. Bacteria possessing an F pilus are termed F+ (donor) cells, while those without it are termed F- (recipient) cells.
  4. During conjugation, an F+ cell transfers a copy of its F plasmid to an F- cell, converting it into an F+ cell.
  5. The formation and function of the F pilus are crucial for horizontal gene transfer among bacteria, contributing to genetic diversity.

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