Question

After RNA primer is removed from the leading strand, why doesn't the leading strand have the end problem?

Answer 1

Each strand of DNA acts as a template for synthesis of new DNA or the replication process.New DNA is synthesized in the 5' to 3' direction only.The anti-parallel nature of DNA makes it replicated in two different ways.One new strand is made as a continuous piece which is called the leading strand the other which is called the lagging strand which is made in small pieces(Okazaki fragments, fragments). Synthesis of either strands requires enzymes (DNA Polymerase, primase, DNA helicase, DNA ligase, and topoisomerase. and primers that can be extended in 5' to 3' direction.The leading strand is having single primer and the DNA is copied continuously without any interruption or break without having an end problem. The lagging strand synthesis is much more mechanistically complicated and it suffers from no.of end problemss Each of the Okazaki fragments of the lagging strand begins replication with its own RNA primer.The high-incidence errors in Okazaki fragments as most of them are synthesized by Pol α which does not contain a proofreading function which will lead to genomic instability, When the replication fork reaches the end of the chromosome the primers are replaced by the DNA and the fragments are joined together to form a continuous stretch of DNA. During the   lagging strand replication process a short stretch of DNA that does not get covered by an Okazaki fragment there is no way to get the fragment replicated along with this  the primer of the last Okazaki fragment that does get made can't be replaced with DNA like other primers.This makes a part of the DNA uncopied in each round of replication, leaving a stretch single-stranded overhanging.This results in DNA alterations.