Final answer:
Cells that undergo cell division continue to have their telomeres shortened because most somatic cells do not make telomerase. Telomeres are regions of the chromosomes necessary for cell division. As telomeres shorten, cells become less able to divide and eventually reach a point where they can no longer divide.
Step-by-step explanation:
Cells that undergo cell division continue to have their telomeres shortened because most somatic cells do not make telomerase. Telomeres are regions of the chromosomes necessary for cell division. As telomeres shorten, cells become less able to divide and eventually reach a point where they can no longer divide.