The G1期, or G1 phase, is a part of the cell cycle that occurs after a cell has divided. During this phase, the cell grows and prepares for DNA replication. It is a crucial time for the cell to gather nutrients and produce proteins necessary for the next stage. In the G1期, the cell also checks for any DNA damage and ensures that it is ready to proceed to the S phase, where DNA synthesis occurs. This phase is essential for maintaining the integrity of the genetic material and ensuring proper cell function.