Why is there a need to produce Okazaki fragments on the lagging strand, but not
ID: 88962 • Letter: W
Question
Why is there a need to produce Okazaki fragments on the lagging strand, but not on the leading strand of DNA? It is substantially more efficient to make several shorter strands rather than one longer strand of DNA. The two parental strands of DNA are antiparallel and DNA polymerase can only synthesize new DNA in the 5' to 3' direction. There is not enough cellular DNA ligase for bonding Okazaki fragments together if they were produced from both parental strands. By having on leading strand and one lagging strand the cell can limit the amount of DNA polymerase used for chromosomal replication. The leading strand opens first, and so Okazaki fragments are not needed. The lagging strand unwinds second resulting in the need to produce Okazaki fragments.Explanation / Answer
The answer is (b)
The reason is on the leading strand DNA replication proceeds along the DNA molecule as the parent double stranded DNA is unowned, but on the lagging strand the new DNA is formed in installments which are later joined together by DNA ligase enzyme. This happens because the enzymes that synthesise the new di and I can only work in One Direction with the parent DNA molecule and the two strands are antiparallel, on the leading strand this route is continuous but on the lagging strand it is discontinuous. DNA is synthesized from 5'to 3' copying the 3' to 5' strand replication is continuous.
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