Q.40 Correctly match the Enzyme with its respective Function.
Enzyme Function
P. Gyrase 1. Removes a damaged base by cleaving the bond between sugar and base
Q. Deadenylase 2. Provides a swivel allowing one DNA strand to rotate around the other
R. Glycosylase 3. Catalyses bond formation between 3′-OH and 5′-phosphate end of nucleotides in duplex DNA
S. DNA ligase 4. Is an exoribonuclease that removes the poly(A) tail
(A) P-2; Q-4; R-1; S-3
(B) P-1; Q-4; R-2; S-3
(C) P-2; Q-1; R-4; S-3
(D) P-3; Q-2; R-1; S-4
Gyrase, deadenylase, glycosylase, and DNA ligase play key roles in DNA replication, repair, and mRNA degradation. The correct matching identifies their precise biochemical functions for accurate exam preparation.
Correct Answer
Option (A) P-2; Q-4; R-1; S-3 provides the right pairings. This matches Gyrase to swivel provision, Deadenylase to poly(A) tail removal, Glycosylase to base damage excision, and DNA ligase to phosphodiester bond formation.
Enzyme Functions
Gyrase relieves DNA supercoiling by creating a swivel for strand rotation during replication. DNA glycosylase initiates base excision repair by cleaving the glycosidic bond between a damaged base and sugar. Deadenylase acts as an exoribonuclease shortening mRNA poly(A) tails to trigger decay. DNA ligase seals nicks in duplex DNA by catalyzing 3′-OH to 5′-phosphate bonds.
Option Breakdown
-
(A) Correct: Aligns all enzymes accurately as per standard molecular biology definitions.
-
(B) Incorrect: Misplaces Gyrase (P-1 is glycosylase’s role) while others fit partially.
-
(C) Incorrect: Swaps Glycosylase (R-4 is deadenylase’s function) disrupting repair matching.
-
(D) Incorrect: Assigns Gyrase wrongly to ligase (P-3) and deadenylase to glycosylase.
| Option | P-Gyrase | Q-Deadenylase | R-Glycosylase | S-DNA Ligase |
|---|---|---|---|---|
| (A) | 2 ✓ | 4 ✓ | 1 ✓ | 3 ✓ |
| (B) | 1 ✗ | 4 ✓ | 2 ✗ | 3 ✓ |
| (C) | 2 ✓ | 1 ✗ | 4 ✗ | 3 ✓ |
| (D) | 3 ✗ | 2 ✗ | 1 ✓ | 4 ✗ |
Exam Relevance
These enzymes appear frequently in GATE Biotechnology for testing DNA metabolism knowledge. Understanding their roles aids in questions on replication forks, repair pathways, and RNA turnover.
