Lagging strand
The lagging strand is that strand of the DNA double helix that is orientated in a 3' to 5' manner. Because of its orientation, opposite to the working orientation of DNA polymerase III which is in a 3' to 5' manner, replication of the lagging strand is more complicated than that of the leading strand.
On the lagging strand, primase "reads" the DNA and adds RNA to it in short, separated segments. In eukaryotes, primase is intrinsic to Pol α.[12] DNA polymerase III or Pol δ lengthens the primed segments, forming Okazaki fragments. Primer removal in eukaryotes is also performed by Pol δ.[13] In prokaryotes, DNA polymerase I "reads" the fragments, removes the RNA using its flap endonuclease domain, and replaces the RNA nucleotides with DNA nucleotides (this is necessary because RNA and DNA use slightly different kinds of nucleotides). DNA ligase joins the fragments together.