Definition of Okazaki Fragments

In the process of DNA replication, the two strands are synthesized in an antiparallel fashion. One strand is synthesized in 5’ to 3’ direction whereas the other strand is formed in 3’ to 5’ direction. The DNA polymerase is capable of adding the deoxyribonucleotides only in 5’ to 3’ direction. Hence, the opposite strand is formed by some small, discontinuous fragments of DNA that are synthesized in the backward direction. These small, discontinuous fragments of DNA are termed as Okazaki fragments.


These fragments are glued together by the action of an enzyme known as DNA ligase and this new daughter strand is called the lagging strand. The replication of this strand is initiated by a small piece of RNA which gets extended by the DNA polymerase. This RNA fragment is known as RNA primer.


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