During gel electrophoresis , which chemical is used for visualized the fragmented DNA -

Options

A. Ethylene bromide
B. NaBr
C. NaCl
D. Ethidium bromide

Answer

**Step-by-Step Solution:**

1. **Understanding Gel Electrophoresis**: Gel electrophoresis is a laboratory technique used to separate DNA fragments based on their size. The DNA fragments are placed in a gel matrix and subjected to an electric field.

2. **Preparation of DNA Fragments**: Before performing gel electrophoresis, DNA is cut into fragments using restriction endonucleases. These enzymes recognize specific sequences in the DNA and cleave them, resulting in smaller DNA pieces.

3. **Movement of DNA in Gel**: DNA is negatively charged due to its phosphate backbone. When an electric field is applied, the DNA fragments migrate towards the positive electrode (anode). Smaller fragments move faster and travel further through the gel compared to larger fragments.

4. **Need for Visualization**: After the separation process, the DNA fragments are not visible to the naked eye. To visualize them, a staining process is required.

5. **Staining the DNA**: Ethidium bromide is the chemical commonly used to stain DNA during gel electrophoresis. It intercalates between the bases of the DNA and fluoresces under UV light.

6. **Visualization Under UV Light**: Once the DNA is stained with ethidium bromide, the gel is exposed to ultraviolet (UV) light. The stained DNA will emit an orange glow, allowing the visualization of the separated DNA fragments as distinct bands.

7. **Conclusion**: The chemical used for visualizing fragmented DNA during gel electrophoresis is ethidium bromide.

**Final Answer**: Ethidium Bromide

---