The G1 phase of the cell cycle is typically the longest period; however in some cases, the embryonic cells are rapidly dividing, meaning it may only last a few minutes. Some nerve cells never leave the G1 stage of the cell cycle.
There are several stages involved in the cell cycle: the G1 phase, S phase and the G2 phase. The G1 phase prepares the cell to undergo the next stage of synthesis. The S phase is where all chromosomes are duplicated and the DNA is replicated. During the G2 phase, the cell prepares itself for mitosis by synthesizing all of the needed components. After this follows the interphase, prophase, metaphase, anaphase and telophase.