Telomerase replicates the ends of chromosomes
Human telomeres ≈ 1,000 repeats of the sequence GGGTTA
Needs to be replenished each time the cell divides
Telomerase recognizes the tip of a telomere and extends it in 5’ – to – 3’ direction
Uses RNA template that is part of the enzyme
The 3’-DNA end of each telomere is always longer than the 5’-end.
This leaves a protruding single-stranded end that loops back forming a t-loop.
A t-loop at the end of a chromosome