There are a few things that turn me on. Two of them are mtDNA and telomeres. Telomeres prevent the ends of chromosomes from fusing when they shouldn’t. They are sequences at the ends of chromosomes, they can be thousands of sequences long. Each time a cell divides it loses the outmost telomere for technical reasons. As subsequent divisions occur more telomeres are lost and eventually there are no more. This is causes the cell to stop division in the future. It is death.
As our bodies age telomeres are eroded until there are no more and the cell dies. Eventually, we die.
And if you have a technical bent, http://tinyurl.com/289w6