Southern blotting cannot be performed without

Options

A. Restriction endonucleases
B. Agarose
C. Monoclonal antibodies
D. Both (1) and (2)

Answer

To answer the question "Southern blotting cannot be performed without," we will analyze the components required for the Southern blotting technique step by step.

### Step-by-Step Solution:

1. **Understanding Southern Blotting**:
Southern blotting is a technique used to detect specific DNA sequences in DNA samples. It was developed by Edwin Southern and involves several key steps.

2. **Requirement of Restriction Endonucleases**:
The first step in Southern blotting is to cut the DNA into smaller fragments. This is done using restriction endonucleases, which are enzymes that act as molecular scissors. They cut DNA at specific sequences, allowing for the isolation of the target DNA fragment.

3. **Gel Electrophoresis**:
After the DNA is cut, the next step is to separate these fragments using gel electrophoresis. This process requires agarose gel, which serves as the medium through which the DNA fragments will migrate when an electric current is applied.

4. **Transfer to Blotting Membrane**:
Once the DNA fragments are separated by size, they are transferred from the gel onto a blotting membrane. This step is crucial for the subsequent detection of the specific DNA sequence of interest.

5. **Role of Monoclonal Antibodies**:
Monoclonal antibodies are not involved in the Southern blotting process. They are typically used in techniques like Western blotting, which is for protein detection, not DNA.

6. **Conclusion**:
Therefore, for Southern blotting to be performed, both restriction endonucleases (to cut the DNA) and agarose (to perform gel electrophoresis) are required. Monoclonal antibodies are not necessary for this technique.

### Final Answer:
Southern blotting cannot be performed without **restriction endonucleases and agarose**. Thus, the correct answer is **option 4: both 1 and 2**.

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