a 20 years young man can look like an 80 years old man.why

a 20 years young man can look like an 80 years old man.why
its due to DNa repair mechanism and some genetic abnormalities in
certain metabolisms.genetics affects ageing also.we ll see
how.normally in DNa replication 5 end of daughter DNa is not formeeway
the usual enzyme DNa polymerase.so such an end strand is called
telomere.its prone to be destroyed easily.so its prevented by
telomerase.its a reverse transcriptase enzyme..its a DNa dependantrna polymerase.
so in old people this enzyme is very less so cells are destroyed
quickly.in cancer cells is is abundant.so cells keep proliferating.
in werners syndrome,telomerase is absent.so a 20 years young man will
appear like an 80 years old man.it is called as cellular senescence