Mitosis StagesMitosis is the phase of the cell cycle where chromosomes in the nucleus are evenly divided between two cells. When the cell division process is complete, two daughter cells with identical genetic material are produced.
Before a dividing cell enters mitosis, it undergoes a period of growth called interphase. Some 90 percent of a cell's time in the normal cellular cycle may be spent in interphase.
View image of a cell in interphase.
- G1 phase: The period prior to the synthesis of DNA. In this phase, the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase.
- S phase: The period during which DNA is synthesized. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.
- G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase.
- In the latter part of interphase, the cell still has nucleoli present.
- The nucleus is bounded by a nuclear envelope and the cell's chromosomes have duplicated but are in the form of chromatin.
- In animal cells, two pair of centrioles formed from the replication of one pair are located outside of the nucleus.