With reference to molecular diagnosis which of the given statements are correct?
(A) PCR is now routinely used to detect HIV in suspected AIDS patients.
(B) Using methods of diagnosis like serum and urine analysis, etc. early detection of disease is possible.
(C) Infection by pathogen can be detected by the presence of antigens or by detecting the antibodies synthesised against the pathogen.
(D) ELISA is based on the principle of antigen-antibody interaction.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (C) and (D) only
Molecular diagnosis means detecting a disease early, at the level of the pathogen’s DNA or proteins. Its main tools are recombinant DNA technology, PCR and ELISA.
(A) PCR is now routinely used to detect HIV in suspected AIDS patients. — Correct. PCR amplifies even a very small amount of the nucleic acid of the virus, so the infection can be detected.
(B) Using methods of diagnosis like serum and urine analysis, etc. early detection of disease is possible. — Incorrect. With such conventional methods, early detection is not possible. That is why PCR and ELISA are used.
(C) Infection by pathogen can be detected by the presence of antigens or by detecting the antibodies synthesised against the pathogen. — Correct. This is the way an ELISA test finds an infection.
(D) ELISA is based on the principle of antigen-antibody interaction. — Correct. The test depends on an antigen binding to its antibody.
NCERT Extract:
Molecular Diagnosis – “… PCR is now routinely used to detect HIV in suspected AIDS patients. It is being used to detect mutations in genes in suspected cancer patients too. It is a powerful techqnique to identify many other genetic disorders. 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. ELISA is based on the principle of antigen-antibody interaction. Infection by pathogen can be detected by the presence of antigens (proteins, glycoproteins, etc.) or by detecting the antibodies synthesised against the pathogen.”
Molecular Diagnosis – “… Using conventional methods of diagnosis (serum and urine analysis, etc.) early detection is not possible. Recombinant DNA technology, Polymerase Chain Reaction (PCR) and Enzyme Linked Immuno-sorbent Assay (ELISA) are some of the techniques that serve the purpose of early diagnosis.”