The first period of the first phase (interphase) of the cell cycle is G1, followed by S and G2, and finally by the mitotic phase.
During G1, the ploidy (the quantity of DNA molecules in the cell) can be represented by the formula 2n (n is the number of DNA molecules in a gamete cell of a given species). During S, DNA duplicates and the quantity of genetic material increases from 2n to 4n. During G2, the quantity remains the same: 4n. After the mitotic phase, the quantity of genetic material decreases to 2n in each daughter cell.
In the G1 phase, there are 12 chromosomes. In the S-phase of the cell cycle, the amount of DNA gets doubled. There is doubling of the chromatids but the chromosomes number remains same. The number of chromosomes in the G2 phase will be same as 12 chromosomes and the number of chromatids will be 24.
