During DNA replication inside a cell, each of the two old DNA
strands serves as a template for the formation of an entire new
strand. Because each of the to daughters of a dividing cell
inherits a new DNA double helix containing one old and one new
strand, the DNA double helix is said to be replicated
“semiconservetively” by DNA polymerase.
Analyses carried out in the early 1960s on whole replicating
chromosomes revealed a localized region of replication that
moves progressively along the parental DNA double helix. Because
of its Y shaped structure, this reactive region is called a
replication fork. At a replication fork, the DNA both new
daughter strand is synthesized by a multienzyme complex that
contains the DNA polymerase.