The third phase is perhaps the most mysterious and least understood: a second resting phase, called G2. Why stop a cell from dividing once it has synthesized a duplicate chromosome? Why waste a freshly synthesized strand of DNA? G2 exists as a final checkpoint before cell division because cells cannot afford chromosomal catastrophes such as translocations, broken arms of DNA, drastic mutations, deletions. This is a time when the cell checks and double-checks the fidelity of DNA replication, guarding against damage to DNA, or a devastating event in a chromosome. A cell showered with
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