There is there an autonomous "cell cycle clock which is composed of cyclin + CDK The amount of cyclins oscillates throughout the cell cycle However the steps of the cycle are linked by negative feedback loops known as"checkpoint control"pathwaysThere is there an autonomous "cell cycle clock" which is composed of cyclin + CDK The amount of cyclins oscillates throughout the cell cycle However, the steps of the cycle are linked by negative feedback loops known as "checkpoint control" pathways