What is the end replication problem?

Answer: The end replication problem refers to the inability of the DNA replication machinery to fully replicate the ends of linear chromosomes, leading to their gradual shortening with each cell division. This occurs due to the limitations of the DNA replication process on the lagging strand, where the terminal part of the parental DNA is not replicated. Over time, this shortening can lead to genomic instability and cellular aging. Telomeres, which are protective structures at the ends of chromosomes, help counteract this issue by acting as a buffer against the loss of vital genetic information. In normal cells, telomeres gradually shorten, eventually leading to cell senescence or apoptosis. However, some cells express telomerase, an enzyme that extends telomeres and allows for a more extended lifespan, which is also frequently found in cancer cells.