What is a telomere?

What is a telomere?

• A. Coding region of a gene
• B. Repetitive noncoding DNA at chromosome ends that protects genes
• C. A protein complex that initiates replication
• D. The site where RNA polymerase binds to start transcription

Answer: (B)

Telomeres are protective caps located at the ends of linear chromosomes. They consist of repetitive, noncoding DNA sequences that do not encode genes, and their main job is to safeguard essential genes from loss during DNA replication and to prevent chromosome ends from being mistaken for DNA breaks. In humans, the repeats are TTAGGG, repeated thousands of times. Because DNA polymerase cannot fully replicate the very ends of linear chromosomes, telomeres shorten with each cell division unless length is maintained by telomerase in certain cell types. When telomeres become too short, cells stop dividing or die, linking telomere length to aging and genome stability. Telomeres are protected by specialized proteins that help hide chromosome ends from DNA damage responses. This is different from the coding regions of genes, which are transcribed and translated; from a protein complex that initiates replication; or from a promoter region where RNA polymerase binds to start transcription.

Telomeres are protective caps located at the ends of linear chromosomes. They consist of repetitive, noncoding DNA sequences that do not encode genes, and their main job is to safeguard essential genes from loss during DNA replication and to prevent chromosome ends from being mistaken for DNA breaks. In humans, the repeats are TTAGGG, repeated thousands of times. Because DNA polymerase cannot fully replicate the very ends of linear chromosomes, telomeres shorten with each cell division unless length is maintained by telomerase in certain cell types. When telomeres become too short, cells stop dividing or die, linking telomere length to aging and genome stability. Telomeres are protected by specialized proteins that help hide chromosome ends from DNA damage responses. This is different from the coding regions of genes, which are transcribed and translated; from a protein complex that initiates replication; or from a promoter region where RNA polymerase binds to start transcription.