Okazaki fragments are formed during the synthesis of
Okazaki fragments are sho, 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 sho 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 ~SS120-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. 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. DNA is synthesised from 5&; to 3&;, so when copying the 3&; to 5&; strand, replication is continuous.
ds DNA
ss DNA
m RNA
t RNA
Metabolism of nucleic acids