Question

Place the following enzymes in the order in which they function in DNA replication: ligase, primase, helicase, and DNA polymerase.

Short answer

The correct order of enzymes functioning during DNA replication process is: Helicase, Primase, DNA Polymerase, and Ligase.

Step-by-step solution

Understanding the role of helicase

Helicase is an enzyme that kick-starts the process of replication by unwinding the double-stranded DNA, breaking the hydrogen bonds between the base pairs. This creates two separate single-stranded DNA templates where the new strands can be synthesized.

Role of primase

Once the DNA strands have been separated, primase adds a short RNA primer sequence to the single-stranded DNA templates. This primer sequence serves as a starting point for DNA polymerase.

Action of DNA polymerase

DNA polymerase then initiates the process of adding new nucleotides to the RNA primer, effectively building the new DNA strands complementary to the single-stranded DNA templates. However, it leaves behind gaps or nicks on one strand called Okazaki fragments.

Role of Ligase

The final enzyme, Ligase, comes into action to glue or 'ligate' the Okazaki fragments together, thereby completing the replication process. It seals the gaps between the fragments making the new DNA strand continuous. This step completes the process of replication.