when nucleotides are added to primers, the primers are extended in ..?

5' to 3' of the daugther strand. 3' to 5' of the parental strand.

DNA polymerase can only add nucleotides to the 3' end of the parent strand because of the OH group on the backbone.

Rocket Dog: The daugther strand is added to the parental 3' semiconservatively by using DNA polymerase going 5' - 3'. The parential strand acts as a template for the production of daughter strand by complementry base pairing.

Leading strand is continous in the 5' - 3' while the lagging strand, the "okasaki fragment" undergoes discontinous production.