2. Okazaki fragments are short, newly synthesized
DNA fragments that are formed on the lagging
template strand during DNA replication.
Okazaki fragments are between 1000 and 2000
nucleotides long in Escherichia coli and are
approximately 150 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 the two
Okazaki fragments into one continuous newly
synthesized complementary strand.
3. On the leading strand DNA replication proceeds
continuously along the DNA molecule, but on the
lagging strand the new DNA is made in fragments,
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 (DNA is synthesized from 5' to
3).
