Living entities use RNA primers to initiate the synthesis of DNA strands. Before the DNA replication takes place, the primer must be synthesized by primase (type of RNA polymerase). The primase adds a complementary RNA primer to the reading template on the lagging and leading strands. A DNA polymerase can extend a newly synthesized strand from the primer terminus.
The DNA replication in the leading strand is as a result of one continuous piece which moves along with the replication fork requiring an initial RNA primer only to synthesize. The template DNA in the lagging strand runs in the 5′→3′ direction. DNA is synthesized in short fragments, backwards, known as the Okazaki fragments. All through the DNA template, the primase intersperses RNA primers which the DNA polymerase utilizes for DNA synthesis in the direction 5′→3′.
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