**Interphase**

During the cell cycle, the DNA content of a cell undergoes changes as the cell progresses through different phases. The cell cycle consists of several phases, including interphase, which is further divided into three subphases: G1 phase, S phase, and G2 phase, followed by the M phase (mitosis).

**G1 Phase**:
During the G1 phase, the cell grows and carries out its normal functions. The DNA content in the cell is at the 2C level, which means that there is a diploid amount of DNA.

**S Phase**:
In the S phase, DNA replication occurs. The DNA molecule unwinds and each strand serves as a template for the synthesis of a new complementary strand. This results in the formation of two identical copies of DNA, each consisting of one original strand and one newly synthesized strand. As a result of DNA replication, the DNA content in the cell doubles to a 4C level.

**G2 Phase**:
After DNA replication, the cell enters the G2 phase. In this phase, the cell prepares for division by further growing and synthesizing necessary proteins and organelles. The DNA content remains at the 4C level during this phase.

**M Phase**:
The M phase, or mitosis, is the phase where the cell divides into two daughter cells. During mitosis, the replicated chromosomes condense and align at the metaphase plate before being separated into two sets. At the end of mitosis, each daughter cell receives an equal amount of DNA, resulting in the DNA content returning to the 2C level.

**Conclusion**:
Therefore, during the cell cycle, the amount of DNA in a cell remains at the 4C level during the S phase and the G2 phase, while it returns to the 2C level after the completion of mitosis. This ensures that each daughter cell receives the correct amount of DNA during cell division.