In which phase of mitosis do spindle microtubules shorten, leading to the separation of sister chromatids toward opposite poles of the cell?

• A. Metaphase
• B. Prophase
• C. Telophase
• D. Anaphase

Answer: (D)

Verified step by step guidance

1. Understand the process of mitosis: Mitosis is the division of a cell's nucleus into two genetically identical nuclei. It consists of several phases: prophase, metaphase, anaphase, and telophase.
2. Review the role of spindle microtubules: Spindle microtubules are structures that help separate chromosomes during mitosis. They attach to the centromeres of sister chromatids and pull them apart.
3. Focus on anaphase: During anaphase, the spindle microtubules shorten, pulling the sister chromatids apart and moving them toward opposite poles of the cell. This ensures that each daughter cell will receive an identical set of chromosomes.
4. Compare anaphase to other phases: In metaphase, chromosomes align at the cell's equatorial plane, but they are not yet separated. In prophase, the spindle apparatus begins to form, and chromosomes condense. In telophase, the chromosomes reach the poles, and the nuclear envelope reforms.
5. Conclude that the correct phase is anaphase: Based on the description of spindle microtubules shortening and separating sister chromatids, this event specifically occurs during anaphase.