Telomeres

Chromosomal aging timers that protect chromosome ends and shorten with each cell division.

Overview

Telomeres are protective DNA-protein structures at the ends of chromosomes that shorten with each cell division.

Key Points

  • Telomeres are repetitive DNA–protein caps (TTAGGG in humans) that prevent chromosome end fusions and loss of essential DNA.
  • They shorten 50–200 bp per division due to the end‑replication problem and oxidative damage.
  • Critically short telomeres trigger senescence or apoptosis via p53/p21 and p16/RB pathways.
  • In large mammals, shorter telomeres limit tumor potential; constitutively long telomeres increase cancer risk.

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