Can you describe the role of cyclin in regulating the cell cycle?

📌 CONCEPT: Cyclin is a regulatory protein that plays a crucial role in the cell cycle by activating the cyclin-dependent kinase (CDK) and thereby facilitating the transition from one phase to the next.

📐 RULE / FORMULA: The rule governing the activation of CDK-cyclin complex is that it must be dephosphorylated to become active.

💡 WORKED EXAMPLE: For instance, in the G1 phase of the cell cycle, as cyclin levels increase, the CDK-cyclin complex becomes dephosphorylated, and its activity increases, allowing the cell to proceed with the cell cycle.

⚠️ COMMON MISTAKE: A common mistake students make is to assume that cyclin directly activates CDK, whereas in reality, the CDK-cyclin complex must be dephosphorylated to become active.