A piece of DNA is subjected to restriction enzyme digestion and the digested sample is electrophoresed. Which statement is correct in the above context?

Options

A. Smallest fragment is present near cathode
B. Largest fragment is present near anode
C. Largest fragment is present in the middle of the gel
D. Smallest fragment is present near anode

Answer

To solve the question regarding the electrophoresis of DNA fragments after restriction enzyme digestion, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electrophoresis**: Electrophoresis is a laboratory technique used to separate DNA fragments based on their size. When an electric current is applied, negatively charged DNA fragments move towards the positive electrode (anode).

2. **DNA Fragment Size and Movement**: In electrophoresis, smaller DNA fragments move faster and travel farther through the gel compared to larger fragments. This is because smaller fragments can navigate through the pores of the gel more easily.

3. **Gel Composition**: The gel used in this process is typically agarose gel, which provides a medium for the DNA fragments to migrate through when an electric current is applied.

4. **Placement of DNA in the Gel**: The DNA samples are loaded into wells created in the gel, and the wells are positioned near the negative electrode (cathode) since DNA is negatively charged.

5. **Direction of Movement**: Once the electric current is turned on, the DNA fragments will migrate towards the anode. The smallest fragments will end up closest to the anode, while the largest fragments will remain closer to the cathode.

6. **Analyzing the Options**: Based on the movement of the DNA fragments:
- The smallest fragment will be found nearest to the anode.
- The largest fragment will be found nearest to the cathode.
- Therefore, the correct statement is that the smallest fragment is present near the anode.

### Conclusion:
The correct statement in the context of the question is: "The smallest fragment is present near the anode."

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