During which phase(s) of cell cycle amount of DNA in a cell remains at 4C level if the initial amount is denoted an 2C

Options

A. `G_(2)` and M
B. `G_(0) and G_(1)`
C. `G_(1)` and S
D. Only `G_(2)`

Answer

To determine during which phase(s) of the cell cycle the amount of DNA in a cell remains at the 4C level, given that the initial amount is 2C, we can analyze the different phases of the cell cycle.

### Step-by-Step Solution:

1. **Understanding the Cell Cycle**: The cell cycle consists of several phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis).

2. **Initial DNA Amount**: The initial amount of DNA is given as 2C. This means that before DNA replication, the cell has a diploid amount of DNA.

3. **S Phase**: During the S phase, DNA replication occurs. The amount of DNA doubles from 2C to 4C. Therefore, at the end of the S phase, the DNA content is at 4C.

4. **G2 Phase**: After the S phase, the cell enters the G2 phase. During this phase, the DNA content remains at 4C as the cell prepares for mitosis.

5. **M Phase**: The M phase involves mitosis and cytokinesis. During this phase, the cell divides, and the DNA is distributed into two daughter cells. At certain points in the M phase, both 4C (the cell preparing to divide) and 2C (the resulting daughter cells) can be present, but the amount of DNA in the original cell does not remain at 4C throughout the entire M phase.

6. **Conclusion**: The amount of DNA in the cell remains at 4C during the G2 phase. It does not remain at 4C during the M phase as the cell divides.

### Final Answer:
The amount of DNA in a cell remains at 4C level during the **G2 phase**.