The double stranded DNA<span> is opened up or “unzipped” to give two single strands of</span>DNA<span> that can be used as templates for </span>replication<span>. </span>DNA polymerase<span> then adds new, free nucleotides to the </span>3<span>' end of the newly-forming strand, elongating it in a 5' to </span>3<span>' direction.</span>