What are telomeres and how do they change with age?

Telomeres are specialized DNA sequences located at the ends of chromosomes that act as protective caps to prevent DNA damage and loss. They consist of repetitive nucleotide sequences and associated proteins. Telomeres gradually shorten as cells divide over time and eventually become critically short, leading to cellular senescence, apoptosis, or impaired cell function.

The shortening of telomeres is a hallmark of aging and is associated with a variety of age-related diseases, such as cardiovascular disease, diabetes, and cancer. Telomere shortening occurs due to the "end replication problem," which is caused by the incomplete replication of the 3' end of DNA strands during cell division. Telomeres are therefore gradually eroded with each round of cell division until they reach a critical length that triggers a cellular response.

Additionally, factors such as oxidative stress, inflammation, and lifestyle habits such as smoking, poor diet, and sedentary behavior can accelerate telomere shortening. These factors can cause DNA damage and activate the DNA damage response pathway, which further shortens telomeres and impairs cell function.

Overall, telomeres play a critical role in maintaining genome stability and cell function. Understanding how telomeres change with age and the factors that influence their length can provide insight into the aging process and potential strategies for preventing age-related decline.