Question

Microtubules are composed of

• A. Tubulin
• B. Actin
• C. Niacin
• D. Myosin

Hint:

Tubulin is the building block of microtubules, which are vital for maintaining cell shape, transport, and cell division processes.

Answer 1

The Correct Option is A

Microtubules are cylindrical structures made from tubulin protein dimers, which consist of alpha and beta tubulin subunits. These microtubules form part of the cytoskeleton and are essential for various cellular functions such as maintaining cell shape, enabling intracellular transport, and facilitating chromosome movement during cell division.

(1) Tubulin:
- Tubulin polymerizes to form microtubules. These microtubules provide structural support and tracks for motor proteins like kinesin and dynein.

(2) Why Other Options Are Incorrect:
- Actin (Option 2) is a protein that forms microfilaments, not microtubules. - Niacin (Option 3) is a vitamin (B3), not a protein, and has no role in the formation of microtubules.
- Myosin (Option 4) is a motor protein that interacts with actin filaments, but it is not involved in the formation of microtubules.

Conclusion: Microtubules are composed of tubulin, which is essential for their structure and function in the cell.