What will be the content of DNA in a somatic cell at `G_(2)` if its meiotic products have 20 picogram of DNA ?

Options

A. 40 pg
B. 20 pg
C. 80 pg
D. 160 pg

Answer

To solve the problem of determining the DNA content in a somatic cell at the G2 phase, given that its meiotic products have 20 picograms of DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Nature of Meiotic Products**:
- Meiotic products (gametes) are haploid. If the meiotic products have 20 picograms of DNA, this means that each gamete contains 20 picograms of DNA.

2. **Determine the Diploid Content**:
- Since gametes are haploid (n), and they are produced from diploid (2n) somatic cells, we can deduce that the diploid somatic cell would have double the amount of DNA found in the gametes.
- Therefore, the diploid content of DNA in the somatic cell is:
\[ 2n = 2 \times 20 \text{ picograms} = 40 \text{ picograms} \]

3. **Analyze the Cell Cycle Phases**:
- The cell cycle consists of several phases: G1, S, G2, and M.
- In the G1 phase, the cell has a diploid (2n) DNA content, which we calculated to be 40 picograms.

4. **DNA Replication in the S Phase**:
- During the S phase of the cell cycle, DNA replication occurs. This means that the amount of DNA doubles.
- After the S phase, the DNA content becomes tetraploid (4n). Therefore:
\[ 4n = 2 \times 40 \text{ picograms} = 80 \text{ picograms} \]

5. **Determine the DNA Content at G2 Phase**:
- At the G2 phase, the cell retains the tetraploid DNA content, which is 80 picograms. Hence, the DNA content in the somatic cell at G2 is:
\[ \text{DNA content at G2} = 80 \text{ picograms} \]

### Final Answer:
The content of DNA in the somatic cell at G2 is **80 picograms**.