why is the synthesis stage (s phase) called synthesis
S phase The major event in S-phase is DNA replication. The goal of this process is to create exactly two identical semi-conserved chromosomes. The cell prevents more than one replication from occurring by loading pre-replication complexes onto the DNA at replication origins during G1 phase which are dismantled in S-phase as replication begins. In synthesis, the enzyme helicase unwinds the DNA double helix, and the enzyme DNA polymerase re-binds free-floating nucleotides to the separate DNA single strands in accordance with the complementary base pairing rule. DNA synthesis can occur as fast as 2000 nucleotides/second [3] and must create fewer than 2 errors (I.e., wrong bases) in 1010 nucleotide additions.[citation needed]