Q.38 Match the enzyme (Column I) with its corresponding function (Column II).
Column I                                           Column II
P. Primase                                        1. RNA dependent RNA synthesis
Q. Reverse transcriptase               2. DNA dependent DNA synthesis
R. RNA Replicase                           3. RNA dependent DNA synthesis
S. DNA Polymerase III                  4. DNA dependent RNA synthesis
(A) P-4; Q-1; R-3; S-2
(B) P-2; Q-1; R-3; S-4
(C) P-3; Q-4; R-2; S-1
(D) P-4; Q-3; R-1; S-2

Primase synthesizes RNA primers using a DNA template, essential for DNA replication initiation. The correct matching pairs each enzyme with its precise nucleic acid synthesis mechanism from the given options.

Correct Answer

Option (D) P-4; Q-3; R-1; S-2 is correct. This aligns Primase with DNA-dependent RNA synthesis, Reverse transcriptase with RNA-dependent DNA synthesis, RNA Replicase with RNA-dependent RNA synthesis, and DNA Polymerase III with DNA-dependent DNA synthesis.​

Enzyme Functions

Primase functions as a DNA-dependent RNA polymerase, creating short RNA primers complementary to the DNA template to provide a 3′-OH group for DNA polymerase extension. Reverse transcriptase copies RNA into DNA, using an RNA template to synthesize complementary DNA (cDNA), crucial in retroviruses. RNA Replicase, found in RNA viruses, replicates RNA genomes via RNA-dependent RNA polymerization. DNA Polymerase III elongates DNA strands using a DNA template during bacterial replication.​

Option Analysis

• (A) P-4; Q-1; R-3; S-2: Incorrect. Q (Reverse transcriptase) mismatches with RNA-dependent RNA synthesis (1), as it performs RNA-dependent DNA synthesis (3).​

• (B) P-2; Q-1; R-3; S-4: Incorrect. P (Primase) does not do DNA-dependent DNA synthesis (2); it synthesizes RNA. S mismatches with RNA synthesis (4).​

• (C) P-3; Q-4; R-2; S-1: Incorrect. P mismatches with RNA-dependent DNA (3). Q does not perform DNA-dependent RNA synthesis (4).​

• (D) P-4; Q-3; R-1; S-2: Correct, as detailed above with precise template-product dependencies.​