What characterizes a telomere?

A telomere is characterized as a repetitive end of a chromosome. Telomeres are protective structures located at the ends of linear chromosomes and are composed of repetitive DNA sequences. These sequences serve to prevent the degradation of genetic information during cell division, as the DNA replication process cannot fully replicate the very ends of linear DNA strands.

Each time a cell divides, a portion of the telomere is lost, which ultimately contributes to the aging process of cells. The repetitive nature of telomeres, typically composed of sequences like TTAGGG in humans, plays a crucial role in maintaining genomic stability and ensuring proper replication and protection of the chromosomes.

In contrast, the other options refer to different aspects of genetic material. For instance, protein-coding regions are sequences within genes that actually code for proteins, while introns are non-coding sections within genes that are spliced out during mRNA processing. The section that initiates replication pertains to origins of replication rather than the end structures like telomeres. Each of these concepts is important but distinct from the role and structure of telomeres.