The diagram illustrates the cell cycle of a mammalian cell. Checkpoints in the mammalian cell cycle stop the cycle from carrying on if errors occur or DNA is damaged. Four checkpoints are given below. 1 Mitosis is prevented when DNA replication is not complete. 2 Anaphase is prevented if chromatids fail to attach correctly to the spindle. 3 DNA replication is prevented when DNA has been damaged. 4 DNA replication ceases if DNA damage has still not been repaired. At which phases of the cell cycle do these checkpoints occur?
Biology 9700 · AS & A Level · Replication and division of nuclei and cells