During which phase of mitosis do the sister chromatids line up in the center of the cell?

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

Answer: (B)

Verified step by step guidance

1. Understand the process of mitosis, which is the division of a eukaryotic cell's nucleus into two genetically identical nuclei. Mitosis consists of several phases: prophase, metaphase, anaphase, and telophase.
2. In prophase, the chromatin condenses into visible chromosomes, and the mitotic spindle begins to form. The nuclear envelope starts to break down.
3. During metaphase, the chromosomes, which consist of two sister chromatids, align at the metaphase plate, which is an imaginary line equidistant from the two spindle poles. This alignment ensures that each new nucleus will receive one copy of each chromosome.
4. In anaphase, the sister chromatids are pulled apart by the spindle fibers and move toward opposite poles of the cell. This separation ensures that each daughter cell will have an identical set of chromosomes.
5. Finally, in telophase, the chromosomes arrive at the poles, and the nuclear envelope re-forms around each set of chromosomes, resulting in two separate nuclei within the cell. The cell is then ready to undergo cytokinesis, which divides the cytoplasm and completes cell division.