DNA polymerase is also highly specific in that it can only synthesize new polynucleotide strands in the 5' to 3' direction-new strands must always run from 5' to 3'. But the two strands of DNA are antiparallel to each other--one runs 3' to 5', the other from 5' to 3'. Both sides have to be replicated. How is this puzzle solved in DNA replication?