What is the end replication problem?

Answer: The end replication problem refers to the inability of the lagging strand to be fully replicated during DNA replication in linear DNA molecules, leading to their shortening with each round of cell division. This occurs because the RNA primers placed at the ends of the lagging strand cannot be replaced with DNA, as there is no space for DNA polymerase to attach and synthesize a new DNA strand. The problem is important because, if unchecked, the continuous shortening of DNA molecules may eventually lead to the loss of vital genes, causing cell death or malfunction. To counteract this issue, cells have evolved protective structures called telomeres and use an enzyme called telomerase to extend the ends of linear DNA molecules, preventing the loss of vital genetic information.