Final answer:
Telomeres are functional DNA segments located at the ends of chromosomes, consisting of repetitive noncoding sequences maintained by the enzyme telomerase, which protects genetic data during cell division.
Step-by-step explanation:
Telomeres are functional DNA segments located at the ends of linear chromosomes. They consist of noncoding repetitive sequences that do not encode any particular genes but are essential for protecting the coding sequences of DNA during cell division. In humans, the sequence TTAGGG is repeated hundreds to thousands of times in these regions. An enzyme called telomerase adds these sequences to the chromosome ends to prevent their shortening during replication, a critical process for maintaining chromosome stability. This function is especially important in stem cells and cancer cells where telomerase activity is higher, enabling these cells to have increased replicative potential.