What chemicals regulate the cell cycle how do they work?

Cyclins are the chemicals that regulate the cell cycle. Cyclins work by regulating the timing of the cell cycle in eukaryotic cell. Cyclins activates cyclin dependent kinases (CDKs) (an enzyme that works by adding negatively charged phosphate groups to other molecules in a process called phosphorylation) by binding to it to form a cyclin-Cdk complex. This complex then functions by acting as a signal to the cell to move to the next cell cycle phase. At the end of the event, the cyclin is degraded, Cdk is deactivated, therefore signaling exit from a specific phase.