The cutting of DNA at specific locations became possible with the discovery of :

Options

A. restriction enzymes
B. probes
C. selectable markers
D. ligases

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks about the discovery that enabled the cutting of DNA at specific locations. This is a fundamental aspect of biotechnology and genetic engineering.

2. **Identifying Key Terms**: The important terms in the question are "cutting of DNA," "specific locations," and "discovery." This indicates that we are looking for a specific tool or enzyme that allows for precise cuts in DNA.

3. **Recognizing the Role of Enzymes**: The cutting of DNA is performed by enzymes known as restriction enzymes. These enzymes recognize specific sequences in the DNA, known as recognition sites or palindromes, and cut the DNA at these sites.

4. **Types of Restriction Enzymes**: Among the various types of restriction enzymes, Type II restriction endonucleases are the most commonly used in recombinant DNA technology. They cut DNA at specific internal sites rather than at the ends, which is why they are referred to as endonucleases.

5. **Importance of Restriction Enzymes**: The discovery of restriction enzymes has been crucial for molecular biology, as they allow scientists to cut DNA into specific fragments. This capability is essential for cloning, gene manipulation, and various other applications in biotechnology.

6. **Conclusion**: Based on the above information, the correct answer to the question is that the cutting of DNA at specific locations became possible with the discovery of restriction enzymes.

**Final Answer**: The cutting of DNA at specific locations became possible with the discovery of restriction enzymes (specifically Type II restriction endonucleases).

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