Which of the following is the most common type of bacterial flagella arrangement in motile bacteria?

Question

Accepted Answer

A. Peritrichous. ## Bacterial Flagella Arrangements

**Key Point:** Peritrichous flagella (distributed all over the cell surface) is the most common arrangement found in motile bacteria, particularly among Gram-negative rods like *Escherichia coli* and *Salmonella*.

### Classification of Flagella Arrangements

| Arrangement | Location | Examples | Frequency |
|---|---|---|---|
| **Peritrichous** | All over the cell surface | *E. coli*, *Salmonella*, *Proteus* | Most common |
| Monotrichous | Single flagellum at one pole | *Vibrio cholerae*, *Pseudomonas* | Less common |
| Lophotrichous | Tuft of flagella at one pole | *Vibrio*, *Bacillus* | Uncommon |
| Amphitrichous | Flagella at both poles | *Bacillus*, *Vibrio* | Rare |

**High-Yield:** In clinical microbiology, the peritrichous arrangement is diagnostically significant because it produces the characteristic "H antigen" (heat-labile) in serological typing of enterobacteria.

**Clinical Pearl:** Motility testing in the laboratory (e.g., hanging drop preparation or motility agar) most commonly demonstrates peritrichous organisms, which show rapid, diffuse movement in all directions.

**Mnemonic:** **PEP** = **P**eritrichous is **E**verywhere, **P**redominant

### Why Peritrichous is Most Common

1. Provides multidirectional movement capability
2. Allows rapid chemotaxis in response to environmental gradients
3. Evolutionarily advantageous for survival and nutrient acquisition
4. Predominates in Enterobacteriaceae, the most clinically relevant motile bacteria

Answer

B. Lophotrichous

Answer

C. Monotrichous

Answer

D. Amphitrichous

Which of the following is the most common type of bacterial flagella arrangement in motile bacteria?

Explanation

Bacterial Flagella Arrangements

Classification of Flagella Arrangements

Why Peritrichous is Most Common

Practice similar questions

Join our NEET PG community

Arrangement	Location	Examples	Frequency
Peritrichous	All over the cell surface	E. coli, Salmonella, Proteus	Most common
Monotrichous	Single flagellum at one pole	Vibrio cholerae, Pseudomonas	Less common
Lophotrichous	Tuft of flagella at one pole	Vibrio, Bacillus	Uncommon
Amphitrichous	Flagella at both poles	Bacillus, Vibrio	Rare