Biology / Unit 6 Bio 1235 short lesson, about 20 seconds
Telomeres and the End-Replication Problem
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The idea
A telomere is a repetitive DNA sequence capping a linear chromosome's end, protecting genes from the shortening lagging-strand synthesis cannot replicate.
In practice
The lagging strand's final Okazaki fragment cannot be primed past the chromosome's end, so telomeric repeats shorten each division.
Where people slip
The end-replication problem arises because lagging-strand synthesis needs a primer beyond where template remains — the leading strand has no such gap.
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