Question

Match the enzyme with its function. 

 

• A. A-2, B-1, C-3, D-4
• B. A-3, B-2, C-4, D-1
• C. A-2, B-3, C-1, D-4
• D. A-4, B-1, C-2, D-3

Hint:

Think of the replication fork as a zipper: Helicase is the slider unzipping it, Topoisomerase untangles the threads ahead, Pol I removes the starting marks, and Ligase glues the final pieces together.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
DNA replication is a complex, coordinated process requiring a suite of highly specific enzymes.
Each enzyme performs a distinct mechanical or chemical task to ensure the accurate copying of the genome.

Step 2: Detailed Explanation:
Let's map each enzyme to its specific functional role during replication.
- DNA ligase (A): This enzyme catalyzes the formation of phosphodiester bonds between adjacent nucleotides.
Its primary role is to join DNA fragments together, such as sealing the nicks between Okazaki fragments.
Thus, A matches with 2.
- DNA polymerase I (B): In prokaryotes, this enzyme possesses a unique 5' to 3' exonuclease activity.
It uses this activity to remove RNA primers from the lagging strand and then fills the gaps with DNA.
Thus, B matches with 1.
- Helicase (C): This is a motor protein that breaks the hydrogen bonds between complementary base pairs.
Its action serves to unwind the double-stranded DNA helix ahead of the replication fork.
Thus, C matches with 3.
- Topoisomerase (D): As helicase unwinds the DNA, it creates severe torsional strain ahead of the fork.
Topoisomerase cuts, rotates, and reseals the DNA backbone to relieve this supercoiling.
Thus, D matches with 4.

Step 3: Final Answer:
Matching these gives the sequence: A-2, B-1, C-3, D-4.
This matches option (A).