Which colour would you find in DNA strands after stain- ing with Ethidium bromide in the presence of UV light ?

Options

A. Red
B. Green
C. Orange
D. Yellow

Answer

To answer the question about the color of DNA strands after staining with Ethidium bromide in the presence of UV light, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ethidium Bromide**: Ethidium bromide is a fluorescent compound commonly used to stain nucleic acids, such as DNA. It intercalates between the bases of DNA.

2. **Application of Gel Electrophoresis**: The DNA fragments are typically separated using a technique called gel electrophoresis. In this process, DNA fragments are loaded into a gel and subjected to an electric field. Since DNA is negatively charged, the fragments will migrate towards the positive electrode.

3. **Separation of DNA Fragments**: During electrophoresis, smaller DNA fragments move faster and travel further in the gel compared to larger fragments. This allows for the separation of DNA based on size.

4. **Staining the DNA**: After the electrophoresis is complete, the separated DNA fragments are stained with Ethidium bromide. This staining is essential for visualizing the DNA under UV light.

5. **Visualization Under UV Light**: When the gel is exposed to UV light, the Ethidium bromide bound to the DNA fluoresces. The fluorescence emitted by Ethidium bromide is typically orange in color.

6. **Conclusion**: Therefore, after staining with Ethidium bromide and exposing to UV light, the color of the DNA strands observed will be orange.

### Final Answer:
The color you would find in DNA strands after staining with Ethidium bromide in the presence of UV light is **orange**.

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