Problem 9 - Objective Biology for NEET

Question

Which of the following is involved in amoeboid movement? (a) Centriole (b) Cilia (c) Flagella (d) Microfilament

Step-by-Step Solution

Answer

The cell component involved in amoeboid movement is (d) Microfilament.

Step 1: Understanding amoeboid movement

Amoeboid movement is the most common mode of locomotion in cells. It involves the formation of temporary projections called pseudopodia (false feet) by the cell. These pseudopodia, by extending and retracting, propel the cell towards a direction.

Step 2: Identifying the involved cell component

When considering which cell components could facilitate the formation and manipulation of pseudopodia, the choice narrows to between Centriole, Cilia, Flagella, and Microfilament. But, it is recognized that Microfilaments, specifically a type called actin filaments, are primarily responsible for this activity. They polymerize to push the cell membrane out during the extension of a pseudopodium, and depolymerize to allow it to retract.

Step 3: Final Step: Choosing the correct answer

Hence based on the described function, Microfilaments (d) are involved in amoeboid movement. Cilia and Flagella are primarily for swimming in fluid medium and Centriole is primarily involved in cell division.

Key Concepts

Pseudopodia

In amoeboid movement, pseudopodia play a crucial role. These are temporary, foot-like extensions of a cell's cytoplasm. Pseudopodia, meaning "false feet," allow a cell to move by reaching out and pulling itself forward. Imagine a cell extending these pseudopodia towards a direction. This action helps the cell creep along its environment.

Some characteristics of pseudopodia include:

• They are dynamic and quickly change shape.
• They allow cells to engulf food particles in a process called phagocytosis.
• They interact with the substrate to propel a cell forward.

Overall, pseudopodia are essential for cellular processes requiring mobility and interaction with the immediate environment.

Microfilament

Microfilaments are thin, rod-like structures in the cell's cytoskeleton. They provide support and mobility to cells. Their composition mainly includes actin proteins, which assemble into linear polymers.

Key functions of microfilaments:

• Support the cell's shape and structure, providing tensile strength.
• Actively assist in various forms of cellular movements, including amoeboid movement.
• Participate in cell division by helping form the mitotic spindle.

In the amoeboid movement, microfilaments are vital. They polymerize and depolymerize, enabling the cell to extend and retract its pseudopodia, pushing the cell along its path.

Actin Filaments

Actin filaments, a specific type of microfilament, are crucial for cell movement and structure. They are composed of globular actin subunits that form a double helix structure. This tight configuration allows them to be both flexible and strong.

Some important aspects of actin filaments include:

• Their polymerization pushes the cell membrane forward, forming pseudopodia.
• They help in cell division and muscle contraction by interacting with myosin.
• Their rapid assembly and disassembly allow dynamic cellular responses.

In amoeboid movement, actin filaments play a pioneering role. By polymerizing, they help project the cell's membrane outward, allowing new pseudopodia to form and retract as needed.