Telomeres and ageing
Telomeres play a role in cellular aging. They dictate how many times the cell can divide though mitosis before essential coding DNA is lost.
Most cells can only divide about 50 to 70 times. Beyond this, the telomere sequence gets so short that the cell stops dividing in order to protect its DNA.
Scientists believe that telomere length influences aging and places an upper limit on the maximum lifespan of an organism.
Diseases that affect telomere length highlight the importance of telomeres in cell death and aging.
People who have the disease dyskeratosis congenita have telomeres that shorten at faster rates than usual. As a result, this disease causes premature aging and death.
In some cells, such as epithelial cells, cell turnover is very high. This seems to contradict the idea that cells can only divide a few times.
These cells originate from a population of self-renewing stem cells. Stem cells are able to divide without losing their telomeres.