What are the end pieces of our chromosomes called that shorten every time our cells divide?

Telomeres are the end pieces of chromosomes that play a crucial role in maintaining chromosomal stability. They consist of repetitive nucleotide sequences that protect the ends of chromosomes from deterioration or from fusion with neighboring chromosomes. Each time a cell divides, these telomeres shorten due to the DNA replication process, which cannot fully replicate the very ends of linear chromosomes. This progressive shortening of telomeres is associated with cellular aging and limited cell division, as critically short telomeres may lead to cell senescence or apoptosis.

In contrast, nucleosomes are units of DNA wrapped around histone proteins that help package DNA into a compact structure within the nucleus, but they are not the protective ends of chromosomes. Histones, similar to nucleosomes, refer to the proteins that play a role in DNA packaging and do not directly relate to the ends of chromosomes. Centromeres are regions of the chromosome that are important for the correct segregation of chromosomes during cell division but are not involved in the protective role of telomeres. The role of telomeres in cellular division and aging highlights their importance in genetics and cell biology.