Question

The number of protofilaments in a microtubule are

• A. 10
• B. 12
• C. 5
• D. 13

Answer 1

Answer: (D)

13

Microtubules are eukaryotic cytoskeletal structures. They are unbranched hollow tubules of indefinite length about 25 nanometers of thickness with 15 nanometer core and boundary formed of 13 helically arranged protofilaments of globular molecules of $\alpha$ and $\beta$ tubulin proteins.

So, the correct answer is '13'