What are the repetitive DNA sequences at the ends of chromosomes called? They are telomeres. Telomeres are repetitive, non-coding DNA regions associated with proteins that protect the ends of linear chromosomes.
In humans and many other vertebrates, the repeating sequence is TTAGGG. These repeats act as a protective buffer because DNA-replication machinery cannot fully copy the very ends of linear chromosomes. Without that buffer, important genetic information could be lost during repeated cell division.
Telomeres also prevent chromosome ends from being mistaken for broken DNA. Specialized proteins help fold and shield the ends, reducing the risk that repair systems will fuse one chromosome to another. Telomeres are therefore more than simple “caps”: they are DNA–protein structures.
Centromeres are a common wrong answer because they are also chromosome regions, but they help attach chromosomes to spindle fibers during cell division. Satellites are repetitive DNA sequences found in particular genomic regions, not the standard name for chromosome-end repeats. Telomerase can extend telomeres in germ cells, some stem cells, and many cancer cells.