I think you are referring to Interphase. Interphase can be divided into three smaller steps -- G1, S, and G2. Gap 1, at its simplest is the cell growing and developing. The cell is also producing some mRNA and making sure everything is available/ready to for the Synthesis (S) phase. S phase is the synthesis, duplication, of the DNA. Once that is complete, the cell enters Gap 2 (G2) which is more or less continued cell growth and production of proteins to make sure everything is set and ready for mitosis. You can think of the entire cell cycle in three broad steps. 1. Interphase and it's parts. 2. Mitosis and its four steps. 3. Cytokinesis. The entire process starts over again with the two new daughter cells, but the DNA duplication is during the S phase of interphase.
The cell cycle is the series of procedures taking place in cells. It leads to cell division and replication (duplication).
DNA Replication occurs during the synthesis process of inter-phase. Its goal is to produce two exact same chromosomes.
In eukaryotes, the cell cycle can be divided into three phases
- Mitotic phase
- Cytokinesis phase
4 distinct phases in the cells cycle are as follow:-
- G1 phase (Period of cell growth)
- S phase (Period when chromosomes are duplicated)
- G2 phase (Period after DNA is duplicated)
- M phase (Divided further into 2 phases; one where chromosomes of cell are divided into two sister cells and other where cells cytoplasm half forming two distinct cells called cytokinesis)