During which mitotic phase do sister chromatids separate?

During anaphase, the sister chromatids separate and move towards opposite poles of the cell. This phase comes after metaphase, where the chromatids align at the cell's equatorial plane, and is crucial for ensuring that each daughter cell receives an identical set of chromosomes. The separation occurs due to the action of spindle fibers, which pull the chromosomes apart, facilitating proper distribution into the new daughter cells.

In the context of the other phases, prophase is when chromosomes condense and become visible, metaphase is when chromosomes are lined up in the middle of the cell, and telophase is characterized by the reformation of nuclear envelopes and the decondensation of chromosomes, none of which involve the separation of sister chromatids. Therefore, anaphase is distinct as the phase where key genetic material is actively being segregated, setting the stage for the eventual division of the cell during cytokinesis.