A single stranded DNA or RNA, tagged with a radioactive molecule is called as:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Probe
Option (1) Primer — Incorrect. Primers are small, chemically made pieces of DNA that bind to the ends of the region to be copied in PCR. DNA polymerase extends them. They start DNA synthesis; they are not radioactive labels for finding a gene.
Option (2) Quencher — Incorrect. A quencher is a molecule that absorbs the light given out by a nearby fluorescent dye, so the dye does not glow. It is not a single strand of DNA or RNA.
Option (3) Reporter — Incorrect. A reporter is a gene or label whose signal, such as a colour or light, is easy to see. It is used to show that another gene is working. It is not the name of a labelled strand that pairs with DNA.
Option (4) Probe — Correct. A probe pairs (hybridises) with its complementary DNA, and the radioactive label then shows up on a photographic film. In this way a probe finds a mutated gene in molecular diagnosis, and a VNTR probe is used in DNA fingerprinting.
NCERT Extract:
Molecular Diagnosis – …
