In
molecular biology,
DNA replication is the biological process of producing two identical replicas of DNA from one original
DNA molecule. This process occurs in all
living organisms and is the basis for
biological inheritance. The cell possesses the distinctive property of division, which makes replication of DNA essential.
DNA is made up of a
double helix of two complementary strands. During replication, these strands are separated. Each strand of the original DNA molecule then serves as a template for the production of its counterpart, a process referred to as
semiconservative replication. Cellular
proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication.
[1][2]
In a
cell, DNA replication begins at specific locations, or
origins of replication, in the
genome.
[3] Unwinding of DNA at the origin and synthesis of new strands results in
replication forks growing bi-directionally from the origin. A number of
proteins are associated with the replication fork to help in the initiation and continuation of DNA synthesis. Most prominently,
DNA polymerase synthesizes the new strands by adding
nucleotides that complement each (template) strand. DNA replication occurs during the S-stage of
interphase.
DNA replication can also be performed
in vitro (artificially, outside a cell). DNA polymerases isolated from cells and artificial DNA primers can be used to initiate DNA synthesis at known sequences in a template DNA molecule. The
polymerase chain reaction (PCR), a common laboratory technique, cyclically applies such artificial synthesis to amplify a specific target DNA fragment from a pool of DNA.
