If a cell is treated with a chemical that inhibits the polymerization of tubulin, at which specific stage of mitosis will the cell cycle be arrested?

Solution

1. Tubulin is the protein subunit required for the assembly of spindle microtubules.
2. Spindle fibers are necessary for the attachment to kinetochores and the alignment of chromosomes.
3. Inhibition of tubulin polymerization prevents the formation of the mitotic spindle.
4. Without a functional spindle, chromosomes fail to align at the equatorial plate, arresting the cell at metaphase.
5. Hence the answer is (B).