Questions: In which phase of mitosis do the sister chromatids separate and move towards opposite poles of the cell? A) prophase B) metaphase C) anaphase D) telophase

The answer is C) anaphase: the sister chromatids separate and move towards opposite poles of the cell.

Explanation for each option:

A) Prophase: This is the first phase of mitosis where the chromatin condenses into visible chromosomes, and the mitotic spindle begins to form. The nuclear envelope also starts to break down. However, sister chromatids do not separate in this phase.

B) Metaphase: During metaphase, the chromosomes line up along the metaphase plate (the cell's equatorial plane). The sister chromatids are attached to spindle fibers from opposite poles, but they do not separate yet.

C) Anaphase: This is the correct phase where the sister chromatids separate. The centromeres split, and the spindle fibers pull the sister chromatids apart, moving them towards opposite poles of the cell.

D) Telophase: In telophase, the separated chromatids reach the opposite poles, and the nuclear envelope re-forms around each set of chromosomes. The chromatids de-condense back into chromatin, and the cell begins to divide. The separation of sister chromatids has already occurred by this phase.

In summary, the separation of sister chromatids occurs during anaphase.