The replication fork is a structure that is opened by DNA helicase within the long helical DNA during DNA replication. It has two branching “prongs”, each of which is made up of a single strand of DNA. One strand is referred to as the leading strand, and the other strand is called the lagging strand. The replication fork is the area where DNA replication actually takes place. Once these two strands are opened and exposed, they serve as the template for DNA polymerase to add matching complementary nucleotides to the growing strand, thus replicating the DNA.