<P> Okazaki fragments are short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication . They are complementary to the lagging template strand, together forming short double - stranded DNA sections . Okazaki fragments are between 1000 and 2000 nucleotides long in prokaryotes (e.g. Escherichia coli) and are roughly 100 to 200 nucleotides long in eukaryotes . They are separated by ~ 120 - nucleotide RNA primers and are unligated until RNA primers are removed, followed by enzyme ligase connecting (ligating) an Okazaki fragment onto the (now continuous) newly synthesized complementary strand . </P> <P> On the leading strand DNA replication proceeds continuously along the DNA molecule as the parent double - stranded DNA is unwound, but on the lagging strand the new DNA is made in installments, which are later joined together by a DNA ligase enzyme . This is because the enzymes that synthesise the new DNA can only work in one direction along the parent DNA molecule and the two strands are anti-parallel . On the leading strand this route is continuous, but on the lagging strand it is discontinuous . </P>

Which enzyme seals the gap between the okazaki fragments