DNA fragments are

Options

A. Neutral
B. Negatively charged
C. Positively charged
D. Either positively or negatively charged depending on their size

Answer

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA is composed of molecules called nucleotides. Each nucleotide consists of three components: a phosphate group, a sugar group, and a nitrogen base.

2. **Identifying the Components of Nucleotides**:
- The four types of nitrogen bases in DNA are adenine (A), thymine (T), guanine (G), and cytosine (C).

3. **Defining DNA Fragments**:
- DNA fragments are pieces of DNA that can vary in size.

4. **Charge of DNA Fragments**:
- DNA fragments are negatively charged due to the presence of phosphate groups in the nucleotides.

5. **Movement in Gel Electrophoresis**:
- During gel electrophoresis, DNA fragments move towards the positive electrode because they are negatively charged.

6. **Size and Movement Speed**:
- Smaller DNA fragments move through the gel faster than larger fragments because of less resistance in the gel matrix.

7. **Conclusion**:
- Therefore, the correct answer to the question "DNA fragments are" is that they are negatively charged.