The organ of locomotion of bacteria:-

Appeared in: AIIMS Manglagiri NO - 2019

Explanation

Flagella are long, thread-like, helical appendages that protrude from the bacterial cell wall.
Their primary function is locomotion. They rotate in a propeller-like fashion to move the bacterium through its environment.
This movement, called motility, allows bacteria to move towards nutrients (chemotaxis) or away from harmful substances.
The structure is composed of a protein called flagellin.

Option A: Fimbriae (or pili) are short, hair-like appendages that are primarily involved in adhesion, allowing bacteria to stick to surfaces, including host cells. They are not used for locomotion.
Option B: The capsule is a gelatinous outer layer that provides protection against the host's immune system (e.g., phagocytosis) and prevents dehydration. It does not have a role in motility.
Option C: Spores (specifically endospores) are dormant, highly resistant structures formed by some bacteria to survive extreme environmental conditions like heat, radiation, and lack of nutrients. They are a survival mechanism, not a means of movement.

Clinical Relevance

Nursing practice connection: Knowing Bacterial structures and their functions helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Bacterial motility is a significant virulence factor. Motile bacteria can spread more effectively within the host, leading to more invasive infections. For example, the motility of Helicobacter pylori allows it to penetrate the stomach's mucus layer and cause ulcers.
The presence of flagella can be used in the laboratory to help identify certain types of bacteria.
What if? If a pathogenic bacterium like Salmonella lost its flagella due to a mutation, its ability to cause gastroenteritis would be significantly reduced. It would struggle to move through the intestinal mucus and reach the epithelial cells to initiate infection.

How to Approach the Question

First, identify the key term in the question: 'organ of locomotion'. This means 'the part used for movement'.
Next, consider the subject: 'bacteria'. The question is asking what part bacteria use to move.
Evaluate each option based on your knowledge of bacterial cell structures:
Fimbriae: Recall these are for 'adhesion' or 'sticking'.
Capsule: Recall this is a 'protective coat'.
Spores: Recall these are for 'survival' or 'dormancy'.

Concept Tested & Keywords

Qa170Z38vzL7xOmkfdUBKt

E6 Microbiology Essentials Sastry 4e Part 1 p. 39-41

E6 Microbiology Applied AnjuDhir 3e Part 1 p. 60-62

Practise the full AIIMS Manglagiri NO - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.