During interphase, the cell grows and makes a copy of its DNA. phase. During G1 phase also called the first gap phase, the cell grows physically larger, copies organelles, and makes the molecular building blocks it will need in later steps. During S phase, the cell synthesizes a complete copy of the DNA in its Nucleus. During G2 phase the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis.