During DNA replication, what is the primary function of primase?

• A. Synthesizes short RNA primers that provide a free $3\prime -OH$ group for DNA polymerase to begin DNA synthesis
• B. Joins Okazaki fragments together by forming phosphodiester bonds between adjacent DNA segments
• C. Adds nucleotides to the end of chromosomes to prevent telomere shortening during replication
• D. Unwinds the parental DNA double helix by breaking hydrogen bonds at the replication fork

Answer: (A)

Verified step by step guidance

1. Understand the role of primase in DNA replication: Primase is an enzyme that synthesizes a short RNA primer complementary to the DNA template strand.
2. Recognize that DNA polymerase, the enzyme responsible for adding nucleotides to form the new DNA strand, cannot initiate synthesis on its own and requires a free 3\' hydroxyl (3\'-OH) group to start adding nucleotides.
3. Identify that the RNA primer synthesized by primase provides this essential free 3\'-OH group, allowing DNA polymerase to begin DNA synthesis.
4. Distinguish primase's function from other enzymes involved in replication, such as DNA ligase (which joins Okazaki fragments), telomerase (which extends telomeres), and helicase (which unwinds the DNA helix).
5. Summarize that the primary function of primase is to synthesize short RNA primers that provide the free 3\'-OH group necessary for DNA polymerase to initiate DNA strand synthesis.