Which polymerase primarily performs bulk polymerization during DNA replication in eukaryotes?

DNA Polymerase δ is the primary enzyme responsible for bulk DNA synthesis during eukaryotic DNA replication. This polymerase plays a crucial role in replicating the lagging strand, which undergoes discontinuous synthesis. DNA Polymerase δ works in conjunction with the replication machinery and is responsible for synthesizing the bulk of the newly formed DNA by extending from the RNA primers laid down by primase.

In eukaryotic cells, DNA replication involves multiple polymerases, each with specific functions. While DNA Polymerase α initiates DNA synthesis by synthesizing short RNA-DNA primers, it does not perform elongation. Instead, it hands off the replication process to DNA Polymerase δ for bulk elongation. DNA Polymerase ε is primarily associated with synthesizing the leading strand, while DNA Polymerase β is involved in DNA repair rather than bulk replication.

Therefore, DNA Polymerase δ's critical role in the synthesis of the lagging strand underlines why it is identified as the primary polymerase for bulk DNA replication in eukaryotic cells.