In electrophoresis , the DNA sample is loaded in the gel

Options

A. away from the wells.
B. towards the positive electrode .
C. towards the negative electrode.
D. Both (A) and (C)

Answer

### Step-by-Step Solution:

1. **Understanding Electrophoresis**: Electrophoresis is a technique used to separate DNA fragments based on their size. It involves the movement of charged particles in an electric field.

2. **Charge of DNA**: DNA molecules are negatively charged due to their phosphate backbone. This is a crucial point because it determines the direction in which the DNA will move during electrophoresis.

3. **Direction of Movement**: Since DNA is negatively charged, it will migrate towards the positive electrode when an electric field is applied. Therefore, the DNA sample must be loaded near the negative electrode (the wells) to allow it to move towards the positive electrode.

4. **Loading the Sample**: The DNA sample is loaded into the wells of the gel, which is positioned near the negative electrode. This is where the DNA will start its journey when the electric current is turned on.

5. **Separation of Fragments**: As the electric current is applied, smaller DNA fragments will move faster and travel further through the gel than larger fragments. This results in the separation of DNA fragments based on size.

6. **Final Visualization**: After the electrophoresis run is complete, the separated DNA fragments can be stained and visualized, often using UV light.

### Conclusion:
In electrophoresis, the DNA sample is loaded in the gel near the wells, which are positioned towards the negative electrode. The correct answer is that the DNA is loaded towards the negative electrode.