Which chemical agent acts as a mitotic spindle poison by binding to tubulin dimers, preventing microtubule assembly and arresting cells at metaphase?
Answer and explanation
Correct answer: B. Colchicine
- Step 1: Colchicine is an alkaloid extracted from the autumn crocus Colchicum autumnale.
- Step 2: It binds with high affinity to free -tubulin heterodimers, preventing their polymerization into functional spindle microtubules.
- Step 3: Without spindle fibers, chromosomes cannot segregate during Anaphase; cells arrest at Metaphase, leading to endopolyploidy or doubling of chromosome sets.
Answer
Colchicine.
Why not the others: Actinomycin D intercalates into DNA and inhibits RNA transcription; Cycloheximide inhibits eukaryotic protein translation by blocking ribosomal translocation; Chloramphenicol inhibits bacterial 50S ribosomal peptidyl transferase.
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