<P> The replication fork is a structure that forms within the nucleus during DNA replication . It is created by helicases, which break the hydrogen bonds holding the two DNA strands together . The resulting structure has two branching "prongs", each one made up of a single strand of DNA . These two strands serve as the template for the leading and lagging strands, which will be created as DNA polymerase matches complementary nucleotides to the templates; the templates may be properly referred to as the leading strand template and the lagging strand template . </P> <P> DNA is always synthesized in the 5' to 3' direction . Since the leading and lagging strand templates are oriented in opposite directions at the replication fork, a major issue is how to achieve synthesis of nascent (new) lagging strand DNA, whose direction of synthesis is opposite to the direction of the growing replication fork . </P> <P> The leading strand is the strand of nascent DNA which is being synthesized in the same direction as the growing replication fork . A polymerase "reads" the leading strand template and adds complementary nucleotides to the nascent leading strand on a continuous basis . </P> <P> The lagging strand is the strand of nascent DNA whose direction of synthesis is opposite to the direction of the growing replication fork . Because of its orientation, replication of the lagging strand is more complicated as compared to that of the leading strand . As a consequence, the DNA polymerase on this strand is seen to "lag behind" the other strand . </P>

What does the replication of dna during interphase ensure during cell replication