The term "Southern Blotting" refers to

Options

A. Transfer of DNA fragments from in vitro cellulose membrane to electrophoretic gel
B. Attachment of probes to DNA fragments
C. Transfer of DNA fragments from electrophoretic gel to nitrocellulose sheet
D. Comparison of DNA fragments from two sources.

Answer

### Step-by-Step Solution:

1. **Understanding Southern Blotting**: Southern blotting is a molecular biology technique used to detect specific DNA sequences in a sample. It involves several key steps that allow for the identification of particular DNA fragments.

2. **Preparation of DNA Sample**: The first step in Southern blotting is to prepare the DNA sample. This involves breaking the DNA into smaller fragments, which can then be analyzed.

3. **Gel Electrophoresis**: After the DNA is fragmented, the next step is to separate these fragments based on their size using gel electrophoresis. This technique allows for the visualization of the different DNA fragments.

4. **Denaturation of DNA**: Once the DNA fragments are separated, the double-stranded DNA is denatured into single strands. This is crucial for the subsequent steps, as the probes will need to bind to single-stranded DNA.

5. **Transfer to Nitrocellulose Membrane**: The next step involves transferring the denatured DNA from the gel to a blotting membrane, specifically a nitrocellulose sheet. This step is essential for the detection of the DNA fragments.

6. **Labeling with Probes**: After the transfer, the DNA on the nitrocellulose membrane is labeled using radioactive or fluorescent probes that are complementary to the specific DNA sequences of interest.

7. **Detection**: Finally, the labeled DNA can be detected through autoradiography or other imaging techniques, allowing researchers to visualize the presence of specific DNA sequences.

8. **Conclusion**: The correct definition of Southern blotting is the transfer of DNA fragments from the electrophoretic gel to a nitrocellulose sheet.

### Final Answer:
The term "Southern Blotting" refers to the transfer of DNA fragments from electrophoretic gel to nitrocellulose sheet.

---