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 1,000 to 2,000 nucleotides long in Escherichia coli and are between 100 to 200 nucleotides long in eukaryotes. They are separated by ~10-nucleotide RNA primers and are unligated until RNA primers are removed, followed by enzyme ligase connecting (ligating) the two Okazaki fragments into one continuous newly synthesized complementary strand.
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. On the leading strand this route is continuous, but on the lagging strand it is discontinuous.
They were originally discovered in 1966 by Kiwako Sakabe and Reiji Okazaki in their research on DNA replication of Escherichia coli. They were further investigated by them and their colleagues through their research including the study on bacteriophage DNA replication in Escherichia coli.
Read more about Okazaki Fragments: Experiments, Biological Function, Okazaki Fragments in Prokaryotes and Eukaryotes
Famous quotes containing the word fragments:
“The instincts of merry England lingered on here with exceptional vitality, and the symbolic customs which tradition has attached to each season of the year were yet a reality on Egdon. Indeed, the impulses of all such outlandish hamlets are pagan still: in these spots homage to nature, self-adoration, frantic gaieties, fragments of Teutonic rites to divinities whose names are forgotten, seem in some way or other to have survived mediaeval doctrine.”
—Thomas Hardy (1840–1928)