Mitotic movements — when do centromeres move toward the poles? During mitosis, at which stage do sister chromatids separate and their centromeres move poleward along the spindle microtubules?

Introduction / Context:
Chromosome segregation requires coordinated movements of centromeres and kinetochores along spindle microtubules. The precise timing of poleward movement is central to faithful genome inheritance.

Given Data / Assumptions:

• Metaphase: alignment at the equator with tension.
• Anaphase: cohesin cleavage and onset of poleward movement.
• Prophase/prometaphase: condensation and kinetochore capture, not separation.

Concept / Approach:

At anaphase onset, separase cleaves cohesin rings, allowing sister kinetochores to move toward opposite spindle poles (anaphase A). Spindle elongation (anaphase B) further increases pole-to-pole distance, completing segregation.

Step-by-Step Solution:

Verification / Alternative check:

Time-lapse microscopy visualizes sudden chromatid separation at anaphase, confirming centromere poleward motion during this phase.

Why Other Options Are Wrong:

Metaphase features tension and alignment without separation; other listed stages precede or follow separation.

Common Pitfalls:

Assuming any spindle activity implies separation; only anaphase executes the poleward movement of centromeres.

Final Answer:

anaphase