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Biomedical Research

A Brief Overview of Telomeres

For centuries, scientists have pondered about the human body and the structures that make us who we are. In recent decades, advances in genetics have helped us understand more about the human genome and the processes by which we are able to live.

By Saharsh Satheesh

Published 1:07 PM EST, Mon May 3, 2021

Introduction

For centuries, scientists have pondered about the human body and the structures that make us who we are. In recent decades, advances in genetics have helped us understand more about the human genome and the processes by which we are able to live. One notable advancement was in the study of telomeres. It had been known that telomeres, which are caps on the end of chromosomes, help protect the chromosome. However, its composition and true use was not well understood.

Cells constantly divide, and every time they divide, the DNA copies as well. When this occurs, the telomeres at the ends wear down. In humans, telomeres consist of a repeating sequence of 5’-TTAGGG-3’. This sequence can be repeated over 3,000 times and some cells can reverse the process of losing telomeres by using the enzyme telomerase, where it functions by adding telomeres. Telomerase is usually inactive in somatic cells but can be active in fetal tissue and germ cells.

Studies

As cells replicate, these telomeres shorten, and studies have shown that this is associated with aging. A paper by Masood A. Shammas explains that “Telomere length in humans seems to decrease at a rate of 24.8–27.7 base pairs per year [12,13]. Telomere length, shorter than the average telomere length for a specific age group, has been associated with increased incidence of age-related diseases and/or decreased lifespan in humans [10,14,15]. Telomere length is affected by a combination of factors including donor age [16], genetic, epigenetic make-up and environment [17–20], social and economic status [21,22], exercise [21], body weight [12,23], and smoking [12,24]. Gender does not seem to have any significant effect on the rate of telomere loss [13]. When telomere length reaches below a critical limit, the cells undergo senescence and/or apoptosis [25,26].”

Thus, according to Shammas, although “telomere length shortens with age, [the] rate of telomere shortening can be either increased or decreased by specific lifestyle factors. Better choice of diet and activities has great potential to reduce the rate of telomere shortening or at least prevent excessive telomere attrition, leading to delayed onset of age-associated diseases and increased lifespan.”

Future Prospects

Much is still to be understood about telomeres and the secrets that they hold. Scientists are currently studying how telomeres may be useful in better understanding and possibly preventing cancer. Cancer cells are able to use telomerase to continuously replicate, but, according to Jerry W. Shay, “inhibition of telomerase may thus represent a novel anticancer therapeutic approach. If we can suppress telomerase, we may be able to drive cancer cells into a growth arrest state. Many laboratories, including [his] own, are studying this at the present time, and the preliminary results are very encouraging.”

Saharsh Satheesh, Youth Medical Journal 2021

References

Shay, Jerry W. “Do the Telomeres in Cancer Cells Shrink?” Scientific American, Scientific American, 8 Jan. 2001, http://www.scientificamerican.com/article/do-the-telomeres-in-cance/.

Shammas, Masood A. “Telomeres, lifestyle, cancer, and aging.” Current opinion in clinical nutrition and metabolic care vol. 14,1 (2011): 28-34. doi:10.1097/MCO.0b013e32834121b1

“Telomere.” Wikipedia, Wikimedia Foundation, 2 Apr. 2021, en.wikipedia.org/wiki/Telomere.

“Telomeres and Telomerase (Article).” Khan Academy, Khan Academy, http://www.khanacademy.org/science/biology/dna-as-the-genetic-material/dna-replication/a/telomeres-telomerase.

“What Is a Telomere?” Facts, The Public Engagement Team at the Wellcome Genome Campus, 25 Jan. 2016, http://www.yourgenome.org/facts/what-is-a-telomere.

By Saharsh Satheesh

Saharsh Satheesh is a junior in high school. He has a passion for biology and plans to study medicine in college.

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