Which of the given statements is correct in the context of observing DNA separated by agarose gel electrophoresis ?

Options

A. DNA can be seen in visible light
B. DNA can be seen without staining in visible light
C. Ethidium bromide stained DNA can be seen in visible light
D. Ethidium bromide stained DNA can be seen under exposure to UV light

Answer

To determine which statement is correct regarding the observation of DNA separated by agarose gel electrophoresis, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Agarose Gel Electrophoresis**:
- Agarose gel electrophoresis is a technique used to separate DNA fragments based on their size. DNA is cut into fragments using restriction enzymes.

2. **Preparation of the Gel**:
- The agarose gel acts as a matrix through which the DNA fragments will migrate when an electric field is applied.

3. **Application of Electric Field**:
- When the electric field is applied, the negatively charged DNA fragments move towards the positive electrode. Smaller fragments move faster and further than larger ones.

4. **Staining the DNA**:
- After electrophoresis, the DNA fragments need to be visualized. Ethidium bromide is commonly used as a fluorescent dye to stain the DNA.

5. **Visualization Under UV Light**:
- The DNA fragments stained with ethidium bromide are not visible under normal light. They can only be observed under ultraviolet (UV) light, where they fluoresce.

6. **Conclusion**:
- Therefore, the correct statement in the context of observing DNA separated by agarose gel electrophoresis is that the DNA fragments can be seen under UV light after being stained with ethidium bromide.

### Final Answer:
The correct statement is that the DNA fragments can be observed under exposure to UV light after staining with ethidium bromide.

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