Question

Drugs such as vincristine and colchicine disrupt mitosis by binding to tubulin and interferes with microtubule assembly and disassembly. Exactly what mitotic structure do these drugs target and what effect would that have on cell division?

• A. The drugs bind the spindle fiber and hinder the separation of chromatins. This promotes the division spontaneously.
• B. The drugs bind the tubulin, thereby inhibiting their division in S phase. This inhibits cell division.
• C. The drugs bind the tubulin, which leads to an error in the chromosome separation. This could lead to apoptosis.
• D. The drugs bind tubulin and inhibit the formation of spindle. This can arrest the cell cycle.

Answer 1

The correct option is D The drugs bind tubulin and inhibit the formation of spindle. This can arrest the cell cycle.

Vincristine and Colchicine binds to the tubulin protein and disrupts the microtubules. Since spindle is made of microtubules, when the drugs bind to tubulin protein they stop the polymerization of tubulin dimers which in turn inhibits the spindle formation. As a result, the chromosomes are unable to separate.