By Erfan Alireza
Chances are you have heard about DNA at some point in your life, the double-stranded goodness that makes all of life possible. For the most part we thought we have fully understood the science behind DNA, ever since DNA was partially discovered in the 1860s and then improved upon nearly a hundred years later by two Americans, James Watson and Francis Crick, however some of our views on DNA structure might be outdated.
What is DNA?
Deoxyribonucleic acid, or more commonly known as ‘DNA’ is a molecule made up of two polynucleotide chains that coil around each other to form the famous double helix structure of DNA that we’re all familiar with and they carry genetic instructions that influence growth, development, functioning and reproduction of organisms.
Polynucleotides are polymers or long chain molecules made up of monomers or “building-blocks” known as nucleotides.
Each nucleotide molecule is composed of a pentose (5-carbon sugar), a phosphate group and a nitrogenous base. The nitrogenous bases are further split into purines and pyrimidines. Purines are the bases with 2-carbon rings (Adenine & Guanine), and pyrimidines are the single carbon ring bases(Thymine, Cytosine and Uracil).
Quadruple stranded DNA:
Our beliefs on the structure of DNA being naturally fixed has changed.
Scientists have recently found a quadruple stranded in a healthy and fully functioning human cell! It's been sixty years that we've discovered the initial structure of DNA and have made unimaginable progress having made that discovery, but this new finding sheds light onto things we previously didn't know about and deemed impossible.This type of DNA had been observed in cancerous cells and in chemically engineered DNA but never in a healthy cell.
This phenomenon occurs in a nucleic acid with a base sequence that is rich in Guanine, and it’s known as a G-quadruplex. The nitrogenous bases found in DNA are complementary to one another (A&T and G&C) and can join together by forming hydrogen bonds between each other, however Guanine has a unique structure making it the only base that can form bonds with itself, which in turn allows for a G-quadruplex to form.
Uses of Quadruple stranded DNA:
So far we know exactly what DNA does but we don't know the science behind what makes a cell express a gene and how it knows how much protein to make. The speculation is that these G-quadruplexes help in holding the nucleic acid open while the DNA is being transcribed (read) and as a result it influences the production and even the amount of proteins made at the ribosomes in a cell.Furthermore research has shown that there is a direct relation between cells the concentration of G-quadruplexes and the process of DNA replication during the ‘S-phase’ of a cell cycle.
By using synthetic molecules that target these quadruplexes and trap/immobilize them it is believed that we can prevent cells from replicating their DNA and as a result stop mitosis from occurring during cell division. This could be a way to prevent the foundation and development of cancerous cells as these quadruplexes are more likely to occur in the genes of cells (oncogenes) that are rapidly and uncontrollably dividing, as like in cancerous cells.
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Conclusion:
The presence of these G-quadruplexes in natural cells used to be a fascination that came about from over 60 years of research, and it opened a world of new ideas and possibilities for us. What will the next 60 years have in store for us? Only time will tell...
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