After electrophoresis the separated DNA fragment can be visualized ethidium bromide gel exposed UV light . These DNA fragments appear as _______ coloured bands :

Options

A. cloning
B. Transformation
C. PCR
D. Clonal selection

Answer

To answer the question regarding the appearance of DNA fragments after electrophoresis when visualized with ethidium bromide under UV light, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electrophoresis**: Electrophoresis is a technique used to separate DNA fragments based on their size. DNA fragments are negatively charged, and when an electric field is applied, they migrate towards the positively charged electrode.

2. **Separation of DNA Fragments**: The smaller DNA fragments move faster and travel further through the gel compared to larger fragments. This results in a separation of DNA fragments according to their size.

3. **Staining with Ethidium Bromide**: After the electrophoresis process, the separated DNA fragments are stained with a compound called ethidium bromide. Ethidium bromide intercalates between the bases of the DNA.

4. **Visualization Under UV Light**: When exposed to ultraviolet (UV) light, the ethidium bromide emits fluorescence, allowing the DNA fragments to be visualized as bands on the gel.

5. **Appearance of DNA Bands**: The DNA fragments appear as bright orange or pink colored bands when viewed under UV light due to the fluorescence emitted by the ethidium bromide.

6. **Conclusion**: Therefore, the correct answer to the question is that the DNA fragments appear as **orange or pink colored bands**.

### Final Answer:
The DNA fragments appear as **orange or pink colored bands**.