During the process of isolation of DNA, chilled ethanol is added to

Options

A. Break open the cell to release DNA
B. Facilitate action of restriction enzymes
C. Remove proteins such as histones
D. Precipitate DNA

Answer

### Step-by-Step Solution:

1. **Understanding the Process of DNA Isolation**:
- DNA isolation involves several steps, including cell lysis, removal of proteins, and precipitation of DNA.

2. **Role of Chilled Ethanol**:
- Chilled ethanol is used during the DNA isolation process to precipitate the DNA. When DNA is mixed with chilled ethanol, it becomes less soluble and precipitates out of the solution.

3. **Mechanism of DNA Precipitation**:
- The addition of chilled ethanol causes the DNA to aggregate and form visible strands. This is because the ethanol reduces the solubility of DNA in the aqueous solution.

4. **Spooling of DNA**:
- Once the DNA has precipitated, it can be collected using a spooling technique. A spooling tool (often a stick or a glass rod) is used to gently collect the precipitated DNA.

5. **Conclusion**:
- The correct answer to the question is that chilled ethanol is added to precipitate the DNA, allowing it to be collected easily.