What is the defining event of anaphase during mitosis?

• A. Sister chromatids are pulled apart to opposite poles
• B. Chromosomes align at the metaphase plate
• C. The cell membrane begins to pinch inwards
• D. The nuclear envelope re-forms around each set of chromosomes

Answer: (A)

Verified step by step guidance

1. Understand the stages of mitosis: Mitosis is divided into several stages: prophase, metaphase, anaphase, and telophase. Each stage has distinct events that occur to ensure proper cell division.
2. Identify the key event of anaphase: During anaphase, the defining event is the separation of sister chromatids. These chromatids are pulled apart by the spindle fibers towards opposite poles of the cell.
3. Differentiate anaphase from other stages: In metaphase, chromosomes align at the metaphase plate, which is different from the separation seen in anaphase. In telophase, the nuclear envelope re-forms, and the cell membrane begins to pinch inwards during cytokinesis, which follows telophase.
4. Focus on the movement of chromatids: The movement of sister chromatids to opposite poles is facilitated by the shortening of microtubules attached to the kinetochores, ensuring each new cell will receive an identical set of chromosomes.
5. Conclude with the significance of anaphase: The separation of sister chromatids during anaphase is crucial for genetic consistency, ensuring that each daughter cell receives an identical set of chromosomes, maintaining genetic stability across cell generations.