Which enzyme is responsible for synthesizing short RNA sequences that serve as primers in DNA replication?

Which enzyme is responsible for synthesizing short RNA sequences that serve as primers in DNA replication?

• A. Ligase
• B. Helicase
• C. Primase
• D. DNA polymerase

Answer: (C)

The enzyme that synthesizes short RNA sequences to serve as primers during DNA replication is primase. Primase is crucial because during DNA replication, the DNA polymerase enzyme cannot initiate synthesis on its own; it requires a primer with a free 3' hydroxyl (OH) group to start adding DNA nucleotides. Primase synthesizes these short RNA primers complementary to the DNA template, allowing DNA polymerase to then extend from the primer and synthesize the new DNA strand. In the context of the other options, ligase is responsible for joining Okazaki fragments on the lagging strand by sealing nicks in the sugar-phosphate backbone of DNA. Helicase unwinds the double-stranded DNA to make the template strands accessible for replication. DNA polymerase synthesizes the new DNA strand by adding nucleotides to the growing chain, but it cannot start the process without the RNA primers provided by primase. This division of roles is essential for the precision and efficiency of DNA replication.

The enzyme that synthesizes short RNA sequences to serve as primers during DNA replication is primase. Primase is crucial because during DNA replication, the DNA polymerase enzyme cannot initiate synthesis on its own; it requires a primer with a free 3' hydroxyl (OH) group to start adding DNA nucleotides. Primase synthesizes these short RNA primers complementary to the DNA template, allowing DNA polymerase to then extend from the primer and synthesize the new DNA strand.

In the context of the other options, ligase is responsible for joining Okazaki fragments on the lagging strand by sealing nicks in the sugar-phosphate backbone of DNA. Helicase unwinds the double-stranded DNA to make the template strands accessible for replication. DNA polymerase synthesizes the new DNA strand by adding nucleotides to the growing chain, but it cannot start the process without the RNA primers provided by primase. This division of roles is essential for the precision and efficiency of DNA replication.