In agarose gel electrophoresis–

Options

A. DNA migrates towards negative electrode
B. Larger molecules migrate faster than smaller molecules
C. Ethidium bromide can be used to visualize the DNA fragments
D. Pink coloured bands of DNA can be visualized when gel exposed to UV light

Answer

**Step-by-Step Solution:**

1. **Understanding the Basics of Agarose Gel Electrophoresis:**
- Agarose gel electrophoresis is a technique used to separate DNA fragments based on their size. The gel acts as a molecular sieve, allowing smaller fragments to move faster than larger ones.

**Hint:** Recall that DNA is negatively charged due to its phosphate backbone.

2. **Analyzing the Options:**
- **Option 1:** "DNA migrates towards negative electrode."
- This statement is incorrect. DNA, being negatively charged, migrates towards the positive electrode (anode).

**Hint:** Think about the charge of DNA and the direction it would move in an electric field.

3. **Evaluating the Size of Molecules:**
- **Option 2:** "Larger molecules migrate faster than smaller molecules."
- This statement is also incorrect. In agarose gel electrophoresis, smaller DNA fragments migrate faster than larger ones due to less hindrance in the gel matrix.

**Hint:** Consider how size affects movement through a gel.

4. **Identifying Visualization Techniques:**
- **Option 3:** "Ethidium bromide can be used to visualize the DNA fragment."
- This statement is correct. Ethidium bromide is a fluorescent dye that intercalates between DNA bases and allows visualization of DNA under UV light.

**Hint:** Remember the role of dyes in visualizing DNA during electrophoresis.

5. **Assessing the Color of DNA Bands:**
- **Option 4:** "Pink colored bands of DNA can be visualized when gel is exposed to UV light."
- This statement is incorrect. The bands of DNA stained with ethidium bromide appear orange when exposed to UV light, not pink.

**Hint:** Recall the typical color associated with ethidium bromide under UV light.

6. **Conclusion:**
- After analyzing all options, the correct answer is that ethidium bromide can be used to visualize the DNA fragments.

**Final Answer:** Ethidium bromide can be used to visualize the DNA fragments.

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