76. Bacteria propels with the help of
    (1) Actin like MreB proteins
    (2) Tubulin flagella
    (3) Flagellin Flagella
    (4) Changes in cytoskeleton

How Do Bacteria Propel Themselves? Understanding the Role of Bacterial Flagella

Introduction

Bacterial motility is a vital trait that allows cells to navigate their environment, move toward nutrients, and escape harmful conditions. The primary organelle responsible for bacterial locomotion is the flagellum, a complex, whip-like protein structure.

Bacterial Propulsion Mechanism

Among the options presented:

1. Actin-like MreB proteins — These proteins are part of the bacterial cytoskeleton and shape maintenance but do not function directly in motility.

2. Tubulin flagella — Tubulin is a eukaryotic cytoskeletal protein; bacterial flagella are not made of tubulin.

3. Flagellin flagella — Correct. Bacterial flagella are primarily composed of the protein flagellin.

4. Changes in cytoskeleton — Although cytoskeletal changes influence cell shape and division, bacterial propulsion relies on flagella rather than cytoskeletal dynamics.

Structure and Function of Bacterial Flagella

• The bacterial flagellum is a helical filament made by polymerization of flagellin.

• It is connected to a basal body that functions as a rotary motor, powered by proton motive force or sodium gradients.

• Rotation of the flagellum propels the bacterium through liquids, allowing swimming or swarming motility.

Summary

Bacteria propel themselves primarily using flagella made of flagellin proteins, making option (3) the correct choice.