Final answer:
The M-Cdk at the end of G2 is triggered by the accumulation of cyclin, which binds to cyclin-dependent kinase (Cdk) to form the active M-Cdk complex. This complex initiates mitosis and cytokinesis.
Step-by-step explanation:
At the end of G2, the M-Cdk (M-phase promoting factor) is triggered by the accumulation of a protein called cyclin. Cyclin binds to cyclin-dependent kinase (Cdk) to form the active M-Cdk complex. The M-Cdk complex then initiates mitosis and cytokinesis, leading to the separation of chromatids and the formation of two daughter cells.