Pure DNA precipated by addition of chilled ethanol can be removed from solution by

Options

A. Elution
B. Gel electrophoresis
C. Spooling
D. PCR

Answer

To answer the question "Pure DNA precipitated by addition of chilled ethanol can be removed from solution by?", we will analyze the options provided and determine the correct method for collecting the precipitated DNA.

### Step-by-Step Solution:

1. **Understanding DNA Precipitation**:
- When chilled ethanol is added to a solution containing DNA, the DNA precipitates out of the solution. This is a common step in DNA extraction protocols.

2. **Evaluating the Options**:
- **Option A: Elution**:
- Elution involves using a buffer to release DNA from a silica membrane, not from a solution with ethanol. Therefore, this option is incorrect.

- **Option B: Gel Electrophoresis**:
- Gel electrophoresis is a technique used to separate DNA fragments based on size using an electric current. It does not involve the removal of precipitated DNA from ethanol. Thus, this option is also incorrect.

- **Option C: Spooling**:
- Spooling is the method where a glass rod is used to collect the precipitated DNA strands from the solution. The DNA strands can be carefully wound around the rod, allowing for the isolation of the DNA. This is the correct method for removing DNA precipitated by ethanol.

- **Option D: PCR (Polymerase Chain Reaction)**:
- PCR is a technique used to amplify DNA, producing millions of copies from a small sample. It does not relate to the collection of precipitated DNA. Therefore, this option is incorrect.

3. **Conclusion**:
- The correct answer is **Spooling**. This method is specifically designed for collecting precipitated DNA after the addition of chilled ethanol.

### Final Answer:
**Spooling**