What are large tandem repeats of noncoding DNA concentrated at centromeres and ends of chromosomes?

• A. Satellite DNA
• B. Telomere DNA
• C. Promoter DNA
• D. Exonic Repeats

Answer: (A)

Think about DNA sequences that are repeated many times in a row and do not code for proteins. These large blocks of tandem repeats sit in the genome in regions that help structure chromosomes, especially around the centromeres and near chromosome ends. This combination of being noncoding, arranged in long tandem arrays, and concentrated in centromeric (and pericentromeric) regions is what defines satellite DNA. It forms highly repetitive, heterochromatic blocks that contribute to chromosome architecture and stability during cell division. Telomere DNA is a different repetitive set that specifically caps chromosome ends, so the broad description of large tandem repeats at centromeres and ends points to satellite DNA.