Gel-Electrophoresis Unit separates the DNA according to their

Options

A. Charge
B. Concentration
C. pH
D. Size

Explanation

**Step-by-Step Solution:**

1. **Understanding Gel Electrophoresis**: Gel electrophoresis is a laboratory technique used to separate DNA fragments based on their physical properties.

2. **Key Factors for Separation**: The separation of DNA in gel electrophoresis occurs primarily due to the following factors:
- Charge
- Size
- Concentration
- pH

3. **Role of DNA Charge**: DNA molecules carry a negative charge due to the phosphate groups in their backbone. This charge is crucial for their movement in an electric field.

4. **Application of Electric Field**: When an electric current is applied, the negatively charged DNA fragments move towards the positive electrode. This movement is influenced by the size of the fragments.

5. **Size of DNA Fragments**: Smaller DNA fragments move faster and travel further through the gel matrix compared to larger fragments. This is analogous to a race where lighter runners (small fragments) can run faster than heavier runners (large fragments).

6. **Conclusion**: Therefore, the primary basis for separation in gel electrophoresis is the size of the DNA fragments. Smaller fragments migrate more quickly and farther than larger ones.

7. **Final Answer**: The Gel-Electrophoresis Unit separates the DNA according to their size.

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