Final answer:
Without telomerase, telomeres at the ends of chromosomes would become progressively shorter with each cell division, leading to potential genetic instability and contributing to aging and diseases.
Step-by-step explanation:
Without telomerase, the chromosomes would lose the protective telomere sequences at their ends with each round of DNA replication, leading to progressively shorter chromosomes and potentially to genomic instability or cell death.
During DNA replication, the enzyme DNA polymerase cannot fully replicate the 3' end of the chromosome's lagging strand. This is because DNA polymerase requires a primer, and once this primer is removed, there is no upstream DNA to provide a 3' end for the attachment of new nucleotides.
Telomerase helps by extending the 3' end of the chromosome, allowing DNA polymerase to complete replication. Without telomerase, telomeres cannot be fully replicated, and they become shorter with each cell division. Eventually, this could lead to the loss of important genetic information and impact cellular functions, potentially contributing to aging and diseases.