Telomere

 Abstract

Telomere = Telo [Greek nouns telos (τέλος) 'end' ] + Mere [Greek (μέρος, root: μερ-) 'part.'], meaning ending part.

Telomere, meaning the ending part, is actually located at the end part of each chromosome.

Telomere protects the end of the chromosome from degradation by being truncated itself instead of chromosome.

It is known that telomere length is getting shortened during the chromosome replication in cell division,

as DNA polymerase cannot continue its duplicating work to the end part of chromosome.

So when duplication of chromosome is done, the end of the chromosome is shortened.

Telomere consists of repetitive nucleotide sequences. For vertebrates, the sequence of telomere nucleotides is TTAGGG.

This TTAGGG sequence is approximately repeated 2,500 times in human telomere.

So the shortened part of chromosome means the repetitive part of telomere, by truncation occurred during cell division to protect genes on chromosomes.

During the lifetime, as individual gets through cell division, the telomere ends become shorter and shorter.

Then when all the telomeres are gone, cells stop the division, chromosomes remain only strands part, then die with aging.

Because of this, telomere is pointed as a determining individual's aging and lifespan.

However, telomeres can be also replenished by an enzyme called telomerase reverse transcriptase.

 

Discovery History

In the early 1970s : First recognization of telomere existence by notifying the shorter ends of chromosomes during replication. (Alexei Olovnikov)

In 1975–1977 : Discovering simple repeated DNA sequences located at end part of chromosomes. (Elizabeth Blackburn, Joseph Gall)

In 2009 : Discovering mechanism for protecting chromosomes by telomere and telomerase. (Blackburn, Carol Greider, and Jack Szostak)

 This discovery was awarded the 2009 Nobel Prize in Physiology or Medicine.

 

Suggested Questions about Telomere and Aging

During the class, some questions involved in telomere and aging were provided by classmates.

1. What is the actual definition of aging?

2. Between biological age and real-time age, which one is real age?

3. Can the truncation of telomere explain all the aging reason?

4.