Cell cycle phases: phase 1 3: interphase the first and longest stage in mitosis comprises 3 phases of the cell, g1 phase cell carries out its function and grows before dna replication. Rna"s protei(cid:374)s a(cid:374)d other t(cid:455)pes of (cid:373)ole(cid:272)ules but dna. Only phase of the cycle that varies in length => whether cells divide rapidly or slowly depends on length of g1 as other phases are uniform. Cells that are not destined to divide enter the g0 phase (the phase of the cell cycle in eukaryotes in which many cell types stop dividing) Some cases where cells in g0 enter g1 and begin dividing. Most cells of the human nervous system stop dividing once fully mature: s phase dna replication and chromosome duplication occurs, including the dna and the chromosomal proteins, and it also continues synthesis of other cellular molecules.