What structure is made of repetitive sequences of non-coding DNA that protect chromosomes?

The structure that is made of repetitive sequences of non-coding DNA that protect chromosomes is the telomere. Telomeres are located at the ends of linear chromosomes and serve several vital functions. Their primary role is to prevent the deterioration of chromosomes or the fusion with neighboring chromosomes, which can lead to genomic instability.

As cells divide, telomeres become shorter due to the way DNA is replicated. If telomeres were absent, the end of chromosomes would be at risk of damage, and important genetic information could be lost during cell division. Therefore, telomeres maintain chromosome integrity and protect genetic data over generations of cell division. This characteristic makes them essential for cellular aging and the prevention of potential cancerous transformations due to genomic instability.

Other options do not fulfill this specific protective role. The chromatid refers to one complete half of a duplicated chromosome, crucial during cell division but not related to chromosome protection. The centromere plays a different function, acting as a region that links sister chromatids and is involved in the separation of chromosomes during cell division. Histones are proteins that package and order DNA into structural units called nucleosomes, but they do not provide the protective function that telomeres accomplish.