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

Options

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

Answer

To solve the question "DNA or RNA segment tagged with a radioactive molecule is called:", we can follow these steps:

### Step-by-Step Solution:

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

2. **Review the Options**: The options provided are:
- a) Plasmid
- b) Vector
- c) Probe
- d) Clone

3. **Analyze Each Option**:
- **Plasmid**: This is a circular piece of DNA that exists independently of chromosomal DNA in bacteria. It often carries genes that provide an advantage, such as antibiotic resistance. However, it is not specifically related to being tagged with a radioactive molecule.
- **Vector**: This term refers to a carrier used to transfer genetic material into a host organism. While vectors can be used in genetic engineering, they do not specifically refer to segments tagged with radioactive molecules.
- **Probe**: A probe is a single-stranded DNA or RNA fragment that is labeled (often with a radioactive molecule) and is used to detect the presence of complementary sequences in a sample. This matches the description given in the question.
- **Clone**: This refers to a genetically identical copy of an organism or gene. Cloning does not imply any radioactive tagging.

4. **Identify the Correct Answer**: Based on the analysis, the term that accurately describes a DNA or RNA segment tagged with a radioactive molecule is "Probe".

5. **Final Answer**: Therefore, the answer to the question is **Probe**.