Leading and lagging strands:

The  primary  scheme   of  replication   of  double-stranded   chromosomal   DNA  in eukaryotes  follows  which for bacterial  DNA replication a lagging strand and leading strand a rare synthesized,  the latter including  discontinuous synthesis through Okazaki fragments. The RNA primers needs are made through DNA polymerase that carries a primase subunit.  The DNA  polymerase  α initiates synthesis   of  the  lagging   strand that  making   first  the  RNA  primer   and  then extending  it with a small region of DNA. The DNA polymerase δ then synthesizes the rest of the Okazaki fragment.  The leading strand is synthesized through DNA polymerase δ. The δ enzyme has 3' → 5' exonuclease activity and so can proof- read the DNA made but DNA polymerase α has no like activity.