During DNA replication the double-stranded DNA helix is separated to single strands by the enzyme DNA helicase. This exposes the nucleic acid bases that encode the genetic sequence. Replication is then initiated from multiple points throughout the chromosome and elongated by the enzyme DNA polymerase, which adds the complementary nucleotide to each nucleotide in the single stranded DNA template. Once the entirety of the chromosome has been replicated, replication is terminated. The process of replication results in two chromosomes that both have one strand from the original chromosome and one strand newly synthesised.