A chromatid is one of two identical strands of DNA
making up a chromosome that are joined at their
centromeres, for the process of nuclear division (mitosis
or meiosis). The term is used till the centromeres remain in
contact. When they separate (during anaphase of mitosis
and anaphase 2 of meiosis), the strands are called daughterchromosomes. The tips of the chromatid are called
telomeres. They prevent the ends of the chromosome from
attaching to other chromosomes. It has been said that after
repeated cell replication, the telomeres get shorter resulting
in cell death. Thus, this means that the way telomeres work
could play a role in determining the lifespan of a cell.