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The leading strand is continuously synthesized and is elongated during this process to expose the template that is used for the lagging strand (Okazaki fragments). During the process of DNA replication, DNA and RNA primers are removed from the lagging strand of DNA to allow Okazaki fragments to bind to.
The lagging strand is the strand of new DNA whose direction of synthesis is opposite to the direction of the growing replication fork. Because of its orientation, replication of the lagging strand is more complicated as compared to that of the leading strand.
After around 20 nucleotides, elongation is taken over by Pol ε on the leading strand and Pol δ on the lagging strand. [103] Polymerase δ (Pol δ): Highly processive and has proofreading, 3'->5' exonuclease activity. In vivo, it is the main polymerase involved in both lagging strand and leading strand synthesis. [104]
There are two problems after leading and lagging strand synthesis: RNA remains in the duplex and there are nicks between each Okazaki fragment in the lagging duplex. These problems are solved by a variety of DNA repair enzymes that vary by organism, including: DNA polymerase I, DNA polymerase beta, RNAse H, ligase, and DNA2.
In DNA replication, the leading DNA strand is continuously extended in the direction of replication fork movement, whereas the DNA lagging strand runs discontinuously in the opposite direction as Okazaki fragments. [7] DNA polymerases also cannot initiate DNA chains so they must be initiated by short RNA or DNA segments known as primers. [5]
For eukaryotes specifically, the mechanism of DNA replication elongation between the leading and lagging strand differs. On the lagging strand, nicks exist between Okazaki fragments and are easily recognizable by the DNA mismatch repair machinery prior to ligation. Due to the continuous replication that occurs on the leading strand, the ...
This asymmetry is due to the formation of the replication fork and its division into nascent leading and lagging strands. The leading strand is synthesized continuously and in juxtapose to the leading strand; the lagging strand is replicated through short fragments of polynucleotide (Okazaki fragments) in a 5' to 3' direction. [6]
DNA Pol δ is an enzyme used for both leading and lagging strand synthesis. [ 2 ] [ 3 ] It exhibits increased processivity when interacting with the proliferating cell nuclear antigen ( PCNA ). As well, the multisubunit protein replication factor C , through its role as the clamp loader for PCNA (which involves catalysing the loading of PCNA on ...