Coordinating Cell Cycle Events

During the cell cycle, cells reproduce and then segregate their chromosomes. The faithful transmission of genetic information rests on two types of coordinations between these processes. First, cells must ensure that rounds of chromosome segregation alternate with rounds of chromosome reproduction by controlling the order of events in the cell cycle. The second type of control ensures that one event is complete before a second event begins. Thus, cells do not enter mitosis until chromosome segregation is complete, and cells do not begin chromosome segregation until the chromosomes have been aligned correctly on the mitotic spindle. In this paper, I review information on the controls that ensure the order and completeness of cell cycle events and present the results of experiments in yeast designed to identify the way in which cells monitor the completion of DNA replication and spindle assembly.