A single-stranded DNA or RNA, tagged with a radioactive molecule (probe) is allowed to hybridise to its complementary DNA in a clone of cells followed by detection using

Options

A. photographic film
B. autoradiography
C. nitrocellulose paper
D. replica plating

Answer

To answer the question regarding the detection method used for a single-stranded DNA or RNA tagged with a radioactive molecule (probe) that has hybridized to its complementary DNA in a clone of cells, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Probe**: A single-stranded DNA or RNA is tagged with a radioactive molecule, which is referred to as a probe. This probe is essential for detecting specific nucleic acid sequences.

2. **Hybridization Process**: The radioactive probe is allowed to hybridize with its complementary DNA in a clone of cells. Hybridization is the process where two complementary strands of nucleic acids bind together.

3. **Detection Method**: To detect the hybridized radioactive probe, we need a suitable detection technique. The most effective method for detecting radioactively labeled structures is through autoradiography.

4. **Explanation of Autoradiography**: Autoradiography is a technique that uses photographic film or a phosphor screen to visualize the location of the radioactive material. When the radioactive probe hybridizes with the complementary DNA, it emits radiation, which exposes the film or screen, allowing us to see where the hybridization has occurred.

5. **Conclusion**: Therefore, the correct answer to the question is that autoradiography is the method used for detection.

### Final Answer:
The detection method used after hybridization of the radioactive probe with complementary DNA is **autoradiography**.