How are DNA fragments visualised during gel electrophoresis? What is elution?

Explanation

**Step-by-Step Solution:**

1. **Understanding Gel Electrophoresis**: Gel electrophoresis is a technique used to separate DNA fragments based on their size. The DNA samples are loaded into a gel matrix, typically made of agarose, and an electric current is applied. The negatively charged DNA moves towards the positive electrode.

2. **Staining the Gel**: To visualize the DNA fragments after electrophoresis, the gel must be stained. A common fluorescent dye used for this purpose is Ethidium Bromide. This dye intercalates between the bases of the DNA.

3. **Exposure to UV Light**: After staining the gel with Ethidium Bromide, the gel is exposed to ultraviolet (UV) light. Ethidium Bromide fluoresces under UV light, allowing the DNA bands to be visualized as bright orange bands against a dark background.

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