Final answer:
The length of telomeres affects an organism's longevity, as they shorten slightly each time a cell divides, which is associated with aging. Telomerase can add back telomere sequences, but most somatic cells do not produce this enzyme, leading to eventual cell aging and death.
Step-by-step explanation:
The longevity of an organism is influenced by the length of its telomeres, which are the protective caps at the ends of chromosomes. These telomeres are composed of repetitive DNA sequences that do not code for any gene; in humans, this sequence is TTAGGG, repeated between 100 to 1000 times. Each time a cell divides, the number of telomere sequences decreases slightly. This is because the DNA replication machinery cannot completely replicate the ends of linear DNA molecules. However, an enzyme called telomerase can help maintain telomere length by adding these repetitive sequences back onto the chromosomes.
Over time, as the telomeres become shorter, the cell's ability to divide is compromised, which leads to aging and eventually cell death when the telomeres are critically short. The discovery of telomerase has enhanced our understanding of cellular aging and has implications for improving human health and longevity. Still, most somatic cells do not produce telomerase, which means telomere shortening is typically associated with the aging process.