The minimum number of restriction sites required to isolate a desired gene by using endonucleases are

Options

A. 1
B. 3
C. 2
D. Many

Answer

To isolate a desired gene using endonucleases, we need to consider how these enzymes function. Here’s a step-by-step solution to the question:

### Step-by-Step Solution:

1. **Understanding Restriction Endonucleases**: Restriction endonucleases are enzymes that cut DNA at specific sequences known as restriction sites. These cuts allow us to isolate specific fragments of DNA.

2. **Identifying the Desired Gene**: To isolate a desired gene, we need to make cuts in the DNA sequence surrounding that gene. This means we need to know where the gene starts and ends.

3. **Making the Cuts**: To isolate a specific fragment of DNA (which contains the desired gene), we need to make two cuts:
- One cut at the beginning of the gene (the start site).
- Another cut at the end of the gene (the end site).

4. **Minimum Number of Restriction Sites**: Since each cut is made at a restriction site, and we need two cuts to isolate the gene, the minimum number of restriction sites required is two.

5. **Conclusion**: Therefore, the minimum number of restriction sites required to isolate a desired gene using endonucleases is **two**.

### Final Answer:
The minimum number of restriction sites required to isolate a desired gene by using endonucleases is **two**.

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