Genomic integrity is required to maintain long life and prevent diseases associated with genomic instability such as “cancer.” The cell cycle is a compilation of well-organized, sequential molecular events, that lead to succession of DNA replication and segregation of replicated chromosomes. Cell cycle checkpoints are the strict regulatory mechanisms that monitor the order, integrity, and fidelity of the main events of the cell cycle. These include growth up to the acceptable cell size, replication, and integrity of the chromosomes, and their accurate segregation in due course of mitosis. Many of these mechanisms are highly conserved, while other studies on higher organisms have shown to control alternative cell fates with a significant impact on tumor suppression. Here, we take into consideration these different checkpoint pathways in a cell cycle and the consequences of their dysfunction on the fate of a cell.