Final answer:
Cyclin-dependent kinases (Cdks) are crucial for cell cycle regulation, as they activate proteins that allow the cell to pass through cycle checkpoints. Active Cdks are formed by binding to cyclins and undergoing phosphorylation, which is a positive feedback system necessary for cell cycle progression.
Step-by-step explanation:
Cyclin-dependent kinases (Cdks) play a crucial role in cell cycle regulation through a positive feedback system. These protein kinases become fully activated when they bind to a cyclin protein and are subsequently phosphorylated by another kinase. The phosphorylation process activates the Cdk/cyclin complex, altering the shape and function of the proteins it targets and ultimately advancing the cell cycle past checkpoints.
The concentrations of cyclins fluctuate throughout the cell cycle, dictating the timing of when Cdk/cyclin complexes form and exert their regulatory effects. These complexes act as positive regulators, ensuring that the cell progresses through various stages of the cell cycle in response to both internal and external signals.
Cdks are responsible for the positive regulation of the cell cycle. They activate proteins that are essential for the cell to pass through checkpoints, operating as part of a complex network of signals and responses that maintain cellular function and replication. Upon completion of their role for a particular phase, the cyclins involved are degraded to allow the cell cycle to continue to the next stage.