Leading and lagging strands?

hivesaeed4

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.

atyy

Usually the daughter strands (but the terminology is not so fixed that you can't say "leading strand replication" or "leading parent strand" or "leading template strand").

http://www.ncbi.nlm.nih.gov/books/NBK26850/ (Fig. 5.8)
http://www.ncbi.nlm.nih.gov/books/NBK21751/ (Fig. 12.9)

Ygggdrasil

As atyy said, "leading" and "lagging" refer to the daughter strands. This is in part because the parent strand can template both leading and lagging strand synthesis. For example, consider a replication bubble. On the side of the bubble, the left side of the bubble, the top parent strand acts as the template for leading strand synthesis while on the right, the same parent strand acts as the template for lagging strand synthesis.

hivesaeed4

That cleared up any confusion I had. Thanks.