Telomeres consist of repetitive sequences at chromosome ends to protect the DNA. Which statement is true about telomeres?

• A. They encode most genes
• B. They are GC-rich promoters
• C. They are centromere-associated
• D. They are repetitive sequences

Answer: (D)

Telomeres are repetitive DNA sequences at the ends of chromosomes that protect the genome from degradation and from being mistaken for breaks during replication. Their defining feature is that they are composed of many repeats of a simple sequence, rather than containing genes. For humans, the repeat is TTAGGG, repeated thousands of times, which also helps form protective structures and recruit the proteins that shield chromosome ends. This makes the statement that telomeres are repetitive sequences the correct description. They do not encode genes, they are not promoters that control transcription, and they are not the same as centromeres, which are involved in chromosome segregation.