What is the term used for a single strand of nucleic acid that is labelled with a radioactive molecule?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Probe
A probe is a single stranded DNA or RNA tagged with a radioactive molecule. It pairs (hybridises) with its complementary DNA in a clone of cells, and the clones are then detected by autoradiography. A clone with a mutated gene does not appear on the photographic film, because the probe cannot pair with the mutated gene. This is how probes help to find mutations.
NCERT Extract:
Molecular Diagnosis – “… 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 autoradiography. The clone having the mutated gene will hence not appear on the photographic film, because the probe will not have complementarity with the mutated gene.”