CDK cell cycle

The cell cycle is the process by which cells replicate themselves. This requires a mechanism to control the cell cycle system. Too much proliferation can lead to cancer, while cells remaining in a quiescent state will result in no replication and cell death with no replacement. The cell cycle operates by activating and deactivating proteins that are required for DNA replication, chromosome segregation and cytokinesis. Two of the common ways to activate and deactivate proteins is through the addition or removal of a phosphate group. These proteins are regulated by kinases, which serve as the master cell cycle regulator. Kinases phosphorylate while phosphatases dephosphorylate. Phosphorylation is not always the driver of activation and can serve to deactivate proteins as well. The main kinase in cell cycle control is the cyclin-dependent kinase, CDK. Cyclin activity is controlled through the presence of cyclin proteins and through protein inhibitors. CDK levels remain constant throughout the cell cycle. The binding partner cyclin is what changes and is being made and degraded throughout the cell cycle to control the stage that is occurring.