Telomeres are controlled by the presence of the enzyme telomerase. The telomere can reach a length of 15,000 base pairs. Telomeres function by preventing chromosomes from losing base pair sequences at their ends. They also stop chromosomes from fusing to each other. Erosion, as mentioned, occurs each time a cell divides.
Addition is determined by the activity of telomerase.
Telomerase is found in fetal tissues, adult germ cells , and also tumor cells. Because these somatic cells do not regularly use telomerase, they age. The result of aging cells is an aging body. If telomerase is activated in a cell, the cell will continue to grow and divide. Cellular aging, or senescence , is the process by which a cell becomes old and dies.