Which of the following is rich in repeats?

The correct answer is that telomeres are rich in repeats. Telomeres are specialized structures at the ends of linear chromosomes, consisting of repetitive nucleotide sequences. In humans, the most common repeat is the TTAGGG sequence, which is repeated anywhere from hundreds to thousands of times.

Telomeres serve essential functions in protecting chromosomes from degradation and preventing them from fusing with each other, which is critical for maintaining genomic stability. As cells divide, telomeres shorten, and this shortening is associated with aging and cell senescence. The repetitive nature of telomeric DNA is what gives them the ability to safeguard genetic material through numerous cellular divisions.

In contrast, euchromatin and heterochromatin represent different forms of chromatin based on their structure and function within the nucleus. While heterochromatin is more densely packed and often contains repetitive sequences, it is not exclusively composed of repeats, making it less accurate compared to the specific context of telomeres. Chromatin is a broader term that encompasses both euchromatin and heterochromatin, and thus does not specifically refer to regions rich in repetitive sequences.

Therefore, the distinctive characteristic of telomeres being rich in repeated sequences highlights their critical biological role and structural makeup.