Question

Which of the following statements is/are TRUE for Colchicine?

• A. It binds to tubulin molecule and disrupts the assembly/polymerization of microtubule.
• B. It inhibits crossover of chromosomes during meiosis.
• C. It inhibits chromosome condensation during Prophase.
• D. It blocks mitotic cells in Metaphase.

Hint:

Colchicine = microtubule inhibitor. Key hallmark: binds tubulin, prevents spindle formation, and causes metaphase arrest — widely used in karyotyping and polyploidy induction.

Answer 1

The Correct Option is A, D

Step 1: Mechanism of colchicine. Colchicine is a plant alkaloid that binds to tubulin, preventing its polymerization into microtubules. Without microtubules, the mitotic spindle cannot form properly, and chromosomes cannot align or separate correctly. Step 2: Evaluate each statement. (A) True — Colchicine binds tubulin and blocks microtubule assembly, thereby disrupting spindle formation. ✔️ (B) False — Crossover events during meiosis occur during prophase I and involve recombination machinery (Spo11, recombinases), not microtubules. Colchicine does not directly inhibit recombination. ❌ (C) False — Chromosome condensation in prophase is driven by condensin and topoisomerases, not microtubules. Colchicine does not affect condensation. ❌ (D) True — Colchicine-treated cells fail to progress past metaphase because spindle microtubules are disrupted, causing a mitotic block at metaphase (metaphase arrest). ✔️ Step 3: Conclusion. Thus, colchicine is correctly described by statements (A) and (D).