During which phase do centrioles move to the poles and the spindle apparatus forms?

During which phase do centrioles move to the poles and the spindle apparatus forms?

• A. G1 phase
• B. S phase
• C. G2 phase
• D. Prophase

Answer: (D)

The event being tested is the setup of the mitotic apparatus as mitosis begins. In prophase, the centrosomes (which contain the centrioles in animal cells) move to opposite poles of the cell, and the spindle apparatus starts to form from the growing microtubules organized there. This is the first stage of mitosis, following interphase (G1, S, and G2), during which the cell is preparing for division but not yet assembling the spindle. The condensation of chromosomes into visible structures also occurs in this phase, signaling the cell’s commitment to chromosome separation.

The event being tested is the setup of the mitotic apparatus as mitosis begins. In prophase, the centrosomes (which contain the centrioles in animal cells) move to opposite poles of the cell, and the spindle apparatus starts to form from the growing microtubules organized there. This is the first stage of mitosis, following interphase (G1, S, and G2), during which the cell is preparing for division but not yet assembling the spindle. The condensation of chromosomes into visible structures also occurs in this phase, signaling the cell’s commitment to chromosome separation.