After electrophoresis the separated DNA fragment can be vishualised 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, "After electrophoresis, the separated DNA fragments can be visualized as ethidium bromide gel exposed to UV light. These DNA fragments appear as _______ coloured bands," 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 move towards the positive electrode when an electric current is applied.

2. **Staining with Ethidium Bromide**:
- After the DNA fragments are separated, they need to be stained to visualize them. Ethidium bromide is a common intercalating agent used for this purpose. It binds to the DNA.

3. **Exposure to UV Light**:
- Once the DNA is stained with ethidium bromide, the gel is exposed to ultraviolet (UV) light. Ethidium bromide fluoresces under UV light.

4. **Observation of Bands**:
- Under UV light, the DNA fragments will appear as colored bands. Specifically, the bands will appear orange due to the fluorescence of the ethidium bromide.

5. **Final Answer**:
- Therefore, the correct answer to the question is: "After electrophoresis, the separated DNA fragments can be visualized as ethidium bromide gel exposed to UV light. These DNA fragments appear as **orange** coloured bands."