The length of telomeres gradually decreases with increasing age and cell division number, which can lead to chromosome instability, so the changes in telomere length are closely linked to cell aging.
In cells divisionchromosome length is shorten for the ending DNA couldn't be replicated completely, and the loss of telomere DNA will lead to senescence and death.
细胞分裂中染色体因其末端的DNA不能完全复制而短缩，使细胞逐渐失去增殖能力，导致细胞衰老、死亡。
3
Cells have two copies of nearly every chromosome (one each from the mother and father) and they must duplicate these during cell division so that the subsequent cells will also have two each.