The amount of data encoded within the human genome – the body’s complete set of genetic instructions – is astounding. The genome not only contains the information necessary to build an organism from the ground up, but also determines how we grow and develop over the course of our lifespan. Each one of our 100,000,000,000,000 cells contains the DNA that determines this process.
DNA Structure
The structure of DNA itself is fascinating and complex. Located within the nucleus, DNA is defined as the chemical code for the human body. DNA is made up of a vast amount of nucleotide bases – chemically speaking, a nucleoside linked to a phosphate group – that provide both the structure and function of the DNA itself. These bases include adenine, guanine, thymine, and cytosine.
Arranged in a very specific coding pattern, nucleotides form single strands of nucleic acid. To fit inside the nucleus of a human cell, DNA coils tightly into chromosomes. Interactions between the chromosomes – particularly on the telomere – keep DNA further coiled into its familiar double helix.
What Is the Telomere and What Does It Do?
The telomere is the very tip of a chromosome. If you picture a chromosome as a rather lopsided “X”, you can imagine these sections of DNA at both ends of each chromosome, on all four tips. Telomeres always consist of the same sequence of nucleotide bases over and over again; for humans, thymine (T), guanine (G), and adenine (A) repeat, forming the same TTAGGG sequence anywhere from 3,000 to 15,000 times.
The telomere has a wide number of vital functions. Functions include:
- Protecting the ends of the chromosome. Much like a cap, the telomere protects the rest of the chromosome from interacting with other, nearby chromosomes.
- Allowing proper replication. During DNA replication, part of each chromosome is lost. The telomere supplies all the bases lost, preventing other parts of DNA from being affected. Without telomeres, entire genes would be lost or eroded during repeated replication.
- Aside from protection, telomeres offer DNA organization, designed to keep DNA properly coiled and within the nucleus of the cell.
How Do Telomeres Function?
The functions of telomeres are made possible by the DNA and DNA-binding proteins located within. When telomere binding proteins function correctly, the bending, looping, and binding of DNA occurs without error, compacting DNA and forming the T-loops that provide protection from interaction with other chromosomes. Other proteins, known as telomerases, have enzymatic functions that restore telomeres after DNA replication.
When proteins denature, problems can occur within the telomere and affect the chromosome and the gene itself. Protein unfolding can disrupt the function of the protein and lead to the degradation of telomeres because the telomere cannot regenerate. Alternatively, disruption and unfolding of the proteins that keep DNA tightly coiled can result in the unfolding of the DNA itself.
How Can Research Help?
Ultimately, research regarding protein unfolding and its effects on the telomere can provide insights into identifying, slowing, and halting telomere degradation. Although telomeres shorten with age, identifying protein issues that speed degradation can be crucial in addressing degradation-related conditions such as heart disease, cancer, diabetes, bone marrow failure, advanced aging, and osteoporosis.
Sources:
https://www.sciencedaily.com/releases/2019/02/190227124840.htm
https://www.yourgenome.org/facts/what-is-a-telomere
https://www.yourgenome.org/facts/what-is-a-genome
