Outline the role of telomeres in preventing the loss of genes from the ends of chromosomes during DNA replication

SouravOctober 29, 2024

Answered step-by-step

Telomeres play a critical role in protecting the ends of chromosomes during DNA replication. Here’s an outline of their functions:

1. Structure of Telomeres: Telomeres are repetitive DNA sequences (typically TTAGGG in humans) at the ends of chromosomes. They do not code for genes but instead act as protective caps.
2. Prevention of Gene Loss: During DNA replication, DNA polymerase cannot fully replicate the ends of chromosomes. This is known as the “end replication problem,” where each replication cycle slightly shortens the chromosome ends. Telomeres buffer against this loss by providing non-coding sequences that can be gradually shortened without affecting essential genes.
3. Protection from DNA Damage: Telomeres protect chromosome ends from being recognized as DNA damage by cellular repair mechanisms, which would otherwise attempt to “repair” them by fusing chromosomes together or degrading their ends.
4. Telomerase Enzyme Function: In cells like stem cells, germ cells, and certain white blood cells, the enzyme telomerase extends telomeres after each division, allowing these cells to divide many times without significant telomere shortening.
5. Role in Cellular Aging: In most somatic (non-reproductive) cells, telomerase is inactive. As telomeres shorten with each division, cells eventually reach a limit called the Hayflick limit, where they stop dividing. This mechanism helps prevent excessive cell division, reducing the risk of genomic instability and cancer.

By maintaining telomere length, cells can replicate without losing essential genetic information from chromosome ends, contributing to genomic stability across cellular generations.