DNA or RNA segment tagged with a radioactive molecule is called :

Options

A. Clone
B. Plasmid
C. Vector
D. Probe

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the term used to describe a DNA or RNA segment that is tagged with a radioactive molecule.

2. **Analyzing the Options**: The options provided are:
- Clone
- Plasmid
- Vector
- Probe

3. **Defining Each Option**:
- **Clone**: A clone refers to a population of genetically identical individuals, usually produced through asexual reproduction. This does not relate to the tagging of DNA or RNA.
- **Plasmid**: A plasmid is a small, extra-chromosomal DNA molecule that can replicate independently, primarily found in bacteria. This also does not pertain to the radioactive tagging of nucleic acids.
- **Vector**: A vector is a carrier, such as a virus or plasmid, that transfers foreign DNA into a host cell. While vectors are important in genetic engineering, they do not specifically refer to radioactive tagging.
- **Probe**: A probe is a radio-labeled single-stranded DNA or RNA segment used to detect specific sequences of nucleic acids. The base sequence of the probe is complementary to the target sequence, allowing it to bind and indicate the presence of that sequence.

4. **Identifying the Correct Answer**: Based on the definitions, the term that best describes a DNA or RNA segment tagged with a radioactive molecule is **Probe**.

5. **Conclusion**: Therefore, the answer to the question is that a DNA or RNA segment tagged with a radioactive molecule is called a **Probe**.

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