Final answer:
Active M-cdk triggers chromatin condensation, nuclear envelope breakdown, spindle fiber formation, and chromatid separation, ensuring proper cell division during M phase.
Step-by-step explanation:
The active M-cdk triggers several crucial events to drive the cell into M phase. These events include (a) the phosphorylation of proteins that cause chromatin condensation into chromatids, (b) the breakdown of the nuclear envelope to allow chromosome segregation, and (c) the formation of spindle fibers essential for chromosome alignment and separation. The M checkpoint ensures that all sister chromatids are correctly attached to spindle fibers before allowing the cell to proceed with anaphase and complete mitotic division. The tension in the spindle apparatus during metaphase indicates proper kinetochore attachment, leading to the activation of separase which allows sister chromatids to separate at the centromeres. Finally, the M-cdk also initiates the breakdown of cyclin which is crucial for the regulation of the cell cycle.