I'm confused regarding one aspect concerning the leading and the lagging strands. Are they the strands which were present before replication occurs (i.e. the original/parent strands) or are they the strands which come into being after replication is completed (i.e. the newly synthesized/daughter strands). Note:- I understand the 5' to 3' and vice versa distinctions/definitions of the two so don't explain in terms of that.