Final answer:
Primase is the enzyme that primes lagging strand synthesis in eukaryotes by creating an RNA primer necessary for DNA polymerase to start replication.
Step-by-step explanation:
In eukaryotic DNA replication, primase is the enzyme responsible for synthesizing the RNA primer on the lagging strand, which is necessary for DNA polymerase to begin synthesis of the new DNA strands. During replication, two strands, the leading strand and the lagging strand, are formed. The leading strand is synthesized continuously in the 5' → 3' direction, while the lagging strand is synthesized in fragments called Okazaki fragments. Each fragment on the lagging strand requires a new RNA primer, which is provided by primase. Afterward, the RNA primers are removed and the gaps filled in, with the nicks being sealed by DNA ligase.
To answer the student's question directly: primase is the enzyme that synthesizes primers on the lagging strand for DNA replication in eukaryotes.