FIGURE 8-43 Standard DNA replication leads to loss of DNA at the 5′ end of each strand of a linear DNA molecule. Replication of the right end of a linear DNA is shown; the same process occurs at the left end (as can be shown by inverting the figure). As the replication fork approaches the end of the parental DNA molecule, the leading strand can be synthesized all the way to the end of the template strand without the loss of deoxyribonucleotides. However, since synthesis of the lagging strand requires RNA primers, the right end of the lagging daughter DNA strand would remain as ribonucleotides, which are removed and therefore cannot serve as the template for a replicative DNA polymerase. Alternative mechanisms must be used to prevent successive shortening of the lagging strand with each round of replication.