A probe is used in which stage of genetic engineering?

Options

A. Cleaving DNA
B. Recombining DNA
C. Cloning
D. Screening

Answer

**Step-by-Step Solution:**

1. **Understanding the Probe**: A probe is defined as a single-stranded sequence of DNA or RNA that is used to detect the presence of complementary sequences in a sample of DNA. This is crucial in genetic engineering for identifying specific sequences.

2. **Analyzing the Stages of Genetic Engineering**:
- **Cleaving DNA**: This stage involves cutting DNA at specific locations, but does not involve the use of probes.
- **Recombining DNA**: This stage involves combining DNA from different sources to create recombinant DNA, but probes are not primarily used here.
- **Cloning**: This process involves producing identical copies of DNA, but probes are not directly utilized in this stage.
- **Screening**: This stage involves searching through a collection of recombinant DNA to identify clones containing a specific recombinant vector. Probes are essential in this stage as they help in locating the desired sequences.

3. **Conclusion**: Based on the definitions and functions of each stage, the correct answer is that a probe is used in the **screening** stage of genetic engineering.

**Final Answer**: A probe is used in the screening stage of genetic engineering.

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