20 Differences between Pili and Flagella

MN Editors

What is Flagella?

Flagella also known as flagellum, which is a lash-like appendage, emerges from the cell body of cells known as flagellates. One cell can contain one or several flagella. This hair-like structures helps in locomotion of a cell. It has a whip-like appearance which propel a cell through the liquid. Some organisms used flagella as a sensory organs which can detect alteration in pH and temperature.

This filamentous structures mainly found in archaea, bacteria, and eukaryotes. The Archaeal flagella are nonhomologous, while the Bacterial flagella are a coiled, thread-like structure, sharp bent, composed of a rotary motor at its base and are consist of the protein flagellin. The flagella of eukaryotic cells are complicated cellular projections that pummel backwards and forward and are found in protist cells, gametes of plants, and animals. The tubulin protein is the main component of eukaryotic flagella.

The helical structure of flegells is composed of flagellin protein. The flagella is made of three parts such as Basal body, Hook, and Filament.

What is Pili?

Pili also known as pilus, it is a hair-like appendage occurs on the surface of many bacteria and archaea. These are mainly found in gram-negative bacteria. Pili is originated from the plasma membrane and its made of pilin protein. The length of a pill is ranges from 0.5- 2 um and the diameter ranges from 5-7. There are two types of Pili such as short attachment pili and long conjugation pili. The short one is known as fimbriae and the long one is known as “F” or sex pili.

Differences between Pili and Flagella/ flagella vs pili

Characters Flagella Pili
Definition Flagella are long, whip like, helical appendages that protrude through the cell membrane. Pili are hallow, non-helical, filamentous appendages that protrude from the surface of cell.
Structure Flagella are Whip like, helical, but not straight structure. Pili are Hair like, non-helical and straight structures.
Length These are long and whip-like. These are short and hair-like.
Thickness Flagella are thicker than pili, 15-20 nm in diameter. These are thin, about 3-10 nm in diameter.
Number Few flagella occur per cell. Numerous pili occur per cell.
Origin Originate from the cell wall. Originate from the cytoplasmic membrane.
Occurrence flagella can occur either polar, lateral or peritrichous. They occur throughout the surface of the cell.
Found in They are found in gram positive and gram negative bacteria. Tey are only found in gram negative bacteria.
Attached to cell wall No yes
Conjugation Not required for conjugation Required for conjugation.
Composition composed of flagellin protein. composed of pilin protein.
Types Three types of flagella occur in nature: bacterial, archaeal and eukaryotic. Two types of pili are found: conjugative and type IV.
Function Responsible for motility and also functions as a sensory organs which can detect alteration in pH and temperature. Responsible for attachment during conjugation and also helps in motility
Motion Flagella exhibit an undulating, sinusoidal motion. A twitching motility is shown by type IV pili.
Size Long about 15 µm Short about 0.2-20 µm
Rigidity More rigid Comparatively less rigid
Motor system Present in flagella. Absent in pili
Organ of adhesion Organ of adhesion absent in flagella. Organ of adhesion present in pili.
Receptors of virus Absent in flagella These acts as receptors of different viruses
Examples Flagella occur in Salmonella. Pili occur in Pseudomonas.
flagella vs pili


  • https://pediaa.com/difference-between-flagella-and-pili/
  • https://byjus.com/biology/flagella/
  • https://biologyreader.com/difference-between-flagella-and-pili.html
  • https://en.wikipedia.org/wiki/Flagellum
  • https://microbiologynote.com/fimbriae-and-pili/#Pili
  • https://microbiologynotes.com/differences-between-flagella-and-pili/
  • https://vivadifferences.com/structural-difference-between-flagella-and-pili/

We hope you've enjoyed reading our latest blog article! We're thrilled to see the positive response it's been receiving so far. We understand that sometimes, after going through an interesting piece of content, you might have questions or want to delve deeper into the topic.

To facilitate meaningful discussions and encourage knowledge sharing, we've set up a dedicated QNA Forum page related to this specific article. If you have any questions, comments, or thoughts you'd like to share, we invite you to visit the QNA Forum.

QNA Forum Page

Feel free to ask your questions or participate in ongoing discussions. Our team of experts, as well as fellow readers, will be active on the forum to engage with you and provide insightful answers. Remember, sharing your thoughts not only helps you gain a deeper understanding but also contributes to the community's growth and learning. We look forward to hearing from you and fostering an enriching discussion. Thank you for being a part of our journey!

Leave a Comment