Final answer:
The lagging strand in DNA replication of linear eukaryotic chromosomes poses a problem because the last primer cannot be replaced with DNA at the ends, leading to progressively shorter DNA strands. This issue is mitigated by telomerase.
Step-by-step explanation:
Issues with Linear DNA Replication
During DNA replication, the lagging strand poses a significant problem due to linear DNA structures in eukaryotic chromosomes. Unlike the continuous synthesis of the leading strand, the lagging strand is synthesized in discontinuous segments known as Okazaki fragments. This process is fine until the replication machinery reaches the end of the chromosome. Here, the RNA primer for the last Okazaki fragment cannot be replaced with DNA, because there is no upstream DNA for a new primer placement, leading to progressively shorter DNA strands with each cell division. However, an enzyme known as telomerase helps to resolve this problem by extending the telomeric regions of the DNA.