Which checkpoint checks that spindle is formed and those organelles needed for mitosis have been created?

• A. G1 checkpoint
• B. G2 checkpoint
• C. M checkpoint
• D. Cytokinesis checkpoint

Answer: (C)

This is the spindle assembly checkpoint. It operates during mitosis to make sure the spindle apparatus is fully formed and that all chromosomes are properly attached to spindle microtubules from opposite poles. Only when each chromosome is correctly attached and under tension will the cell move from metaphase into anaphase, preventing mis-segregation of chromatids. This checkpoint effectively confirms that the mitotic machinery needed for chromosome separation is ready, which aligns with ensuring the spindle is formed and the necessary mitotic components are in place. The G2 checkpoint, by contrast, primarily checks that DNA replication is complete and undamaged before entering mitosis, and other checkpoints act later in cytokinesis.