Gap or growth phase – The non-replication phases of the cell cycle when DNA is not being duplicated. There are three: G-0 is the quiescent, non-proliferation phase in the cell cycle that follows in mature cells just after G-1. G-1 is the first of the interphase portions of the cell cycle that occurs just after cell mitosis. During this phase the enzymes required for S-phase are produced. G-2 is the phase between the completion of S-phase when all chromosomal material has been replicated and mitosis. During htis phase the chromosomal material is checked for completion and correctness of replication.