What is the following is correct for the movement of DNA fragments on agarose gel during gel electrophoresis ?

Options

A. The larger the fragment size, the farther it moves
B. The smaller the fragment size , the farther it moves
C. Positively charged fragments move to farther end
D. Negatively charged fragments do not move

Answer

To solve the question regarding the movement of DNA fragments on agarose gel during gel electrophoresis, we will analyze the principles of electrophoresis and the behavior of DNA fragments based on their size and charge.

### Step-by-Step Solution:

1. **Understanding Gel Electrophoresis**:
- Gel electrophoresis is a technique used to separate DNA fragments based on their size. An agarose gel matrix is used for this separation.

2. **Charge of DNA**:
- DNA molecules have a uniform negative charge due to their phosphate backbone. When an electric field is applied, the negatively charged DNA will migrate towards the positive electrode.

3. **Separation Based on Size**:
- The movement of DNA fragments through the agarose gel is influenced by their size. Smaller fragments can navigate through the pores of the gel more easily than larger fragments.

4. **Movement of DNA Fragments**:
- When the electric field is applied, smaller DNA fragments will move faster and travel farther through the gel compared to larger fragments, which will move more slowly and not travel as far.

5. **Evaluating the Options**:
- The options provided in the question are:
1. The larger the size of the fragment, the farther it will move.
2. The smaller the size of the fragment, the farther it will move.
3. Positively charged fragments move to the farther end, negatively charged fragments do not move.
- Based on our understanding, the second option is correct: "The smaller the size of the fragment, the farther it will move."

### Conclusion:
The correct statement regarding the movement of DNA fragments on agarose gel during gel electrophoresis is that smaller DNA fragments move farther than larger ones due to their ability to navigate through the gel matrix more easily.

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