Final answer:
Cyclins and cyclin-dependent kinases (Cdks) interact to allow passage of the G2 checkpoint by forming a complex that phosphorylates other proteins involved in advancing the cell to the next phase of the cell cycle.
Step-by-step explanation:
Cyclins and cyclin-dependent kinases (Cdks) are two groups of proteins that interact to allow passage of the G2 checkpoint in the cell cycle. Cyclins regulate the cell cycle when they are tightly bound to Cdks. The fully activated Cdk/cyclin complex must be phosphorylated in specific locations to activate the complex. This complex then phosphorylates other proteins involved in advancing the cell to the next phase of the cell cycle.