Flagella vs. Pili

Differences between Flagella and Pili 4.62/5 (78)

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Differences between Flagella and Pili

Flagella are long thin appendages free at one end and attached to the cell at the other end. Flagella actually extend from the interior of the cell body. They are mostly composed of flagellin protein.

Pili are short, thick straight hair like surface appendages. They are found in gram negative bacteria. They are mostly composed of pilin protein.

Flagella vs. Pili

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

S.N. Characteristics Flagella Pili
1 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.
2 Structure Helical but not straight. Straight non helical.
3 Length Long whip like. Short and hair like.
4 Thickness Comparatively thicker than pili (15-20nm in diameter). Thinner than flagella (3-10nm in diameter).
5 Number Lesser than pili. Numerous.
6 Occurrence May be polar or lateral or peritrichous. Throughout the surface of cell.
8 Found in Both Gram positive and Gram negative bacteria. Gram negative bacteria.
9 Made up of Flagellin protein Pilin protein
10 Attached to cell wall No Yes
11 Origin Cytoplasmic membrane Cell wall
12 Organ of adhesion Absent present
13 Required for conjugation No Yes
14 Types 3 types: Bacterial, Eukaryotic and Archaeal. 2 types: Conjugative and Type IV.
15 Function Responsible for motility but can also be used to sense certain temperature and chemicals or metals. Responsible for attachment, transfer of DNA to other cell during bacterial conjugation i.e. genetic exchange. Also perform motility.
16 Motion Wave like, undulating, sinusoidal. Rotation much like a propeller of a boat motor. Twitching motility, performs by type IV pili.
17 Examples Salmonella Pseudomonas

Differences between Flagella and Pili

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