Telomeres and Replication: Part 3

At the end of a chromosome, however, there is no upstream DNA template for RNA primer formation, and the 3′ end of the template DNA cannot be replicated. Therefore, each time a cell replicates DNA in order to divide, a small stretch of DNA sequence is lost from the ends of each chromosome.

D-N-A strand marked with 5 prime and 3 prime. A large red X covers primase and the R-N-A primer arrow next to a faded D-N-A polymerase and D-N-A replication arrow.