Question

which of the following is about 25nm in diameter and form mitotic spindles?

a. intermediate filaments

b. microfilaments

c. keratin

d. microtubules

e. actin

Answer 1

d. microtubules

The microtubules, the third main part of the cytoskeleton, are solid hollow rods with a diameter of around 25 nm. Microtubules are dynamic structures which undergo continuous cell assembly and disassembly. They help both to decide the shape of cells and in a number of cell motions, including some types of cell locomotion, organel intracellular transport and chromosome separation during mitosis

Two wheel-shaped protein structures at the start of nuclear division called centrioles place themselves at opposite ends of the cell creating cell poles. Large protein fibers called microtubules stretch in all possible directions from the centrioles, creating what is considered a spindle.