BIOLOGY - DNA REPLICATION
DNA replication is the process of producing two identical copies of DNA from one
parental DNA molecule which occurs prior to cell division. It starts by splitting the double-
stranded DNA into two single strands in the direction of the replication fork, an action done by
the enzyme called helicase. After that, single-stranded DNA-binding proteins bind to the two
single strands of DNA to prevent them from pairing up again. Next, the DNA primase marks up
the 5' area where DNA polymerization should start. The complementary strands will then be
synthesized by the DNA Pol δ for the leading strand and DNA Pol α for the lagging strand. The
replication in the leading strand is continuous since its direction is the same as that of the
replication fork, whereas, in the lagging strand, okazaki fragments are formed because the
direction of the replication is opposite to that of the replication fork. These okazaki fragments are
nicked by DNA ligase for replication to continue. After the synthesis is done, the large subunit
of DNA Pol α goes back to remove the primers via 5' to 3' exonuclease activity. When there are
errors in the synthesis, DNA Pol β comes to repair those.
DNA replication is the process of producing two identical copies of DNA from one
parental DNA molecule which occurs prior to cell division. It starts by splitting the double-
stranded DNA into two single strands in the direction of the replication fork, an action done by
the enzyme called helicase. After that, single-stranded DNA-binding proteins bind to the two
single strands of DNA to prevent them from pairing up again. Next, the DNA primase marks up
the 5' area where DNA polymerization should start. The complementary strands will then be
synthesized by the DNA Pol δ for the leading strand and DNA Pol α for the lagging strand. The
replication in the leading strand is continuous since its direction is the same as that of the
replication fork, whereas, in the lagging strand, okazaki fragments are formed because the
direction of the replication is opposite to that of the replication fork. These okazaki fragments are
nicked by DNA ligase for replication to continue. After the synthesis is done, the large subunit
of DNA Pol α goes back to remove the primers via 5' to 3' exonuclease activity. When there are
errors in the synthesis, DNA Pol β comes to repair those.
