Write a note on DNA replication.

Explanation

(i)DNA molecule produces exact copies of its own structure during replication process.
(ii)The two strands of a DNA molecule have complementary base pairs.The nucleotides of each strand provide the information needed to produce its new strand.
Origin of replication:
(i)The specific points on the DNA,where the replication begins, is the origin of replication.
(ii)The two strands open and separate at this point forming the replication fork.
Unwinding of DNA molecule,
(i)The enzyme called helicase,bind to the origin of replication site.They separate the two strands of the DNA.
(ii)The enzyme called topoisomerase seperates the double helix above the replication fork and removes the twists formed during the unwinding process.
(iii)Each of the separatd DNA strands strands function as template.
Formation of RNA primer:An RNA primer is a short segment of RNA nucleotides,the primer is synthesized by the DNA template close to the origin of replication.
Synthesis of new complimentary strand from the parent strand:
(i)After the formation of RNA primer,nucleotides are added with the help of an enzyme DNA polymerase and new complimentary strand of DNA is formed from each of the parent strand.The
synthesis is unidirectional.
(ii)In one strand ,the daughter strand is synthesized as a continuous strand which is called leading strand.
(iii)In the other strand,short segments of DNA are synthesized .This strand is called lagging strand.
(iv)The short segments of DNA are called Okazaki fragments .The fragments are joined together by the enzyme DNA ligase.
(v)The replication stop when the replication fork of the two sides meet at a site called terminus which is situated opposite to origin of replication site.