By Catherine Ann Joy
Quantum mechanics is a dimension of science that illustrates the behavior of energy, waves, sub-atomic particles mathematically. It was founded by a group of scientists in the 1920’s to uncover more about the physical properties of nature. One of the founders, Erwin Schrödinger, wrote a book titled ‘What is Life?’ in 1944 where he claimed that there is a radical difference in the random motion of atoms at the molecular level between living and nonliving things. Schrödinger initiated the idea that quantum mechanics had a role in solving DNA mutation before the structure of DNA was discovered by Francis Crick and James Watson in 1953. He famously said, “the inheritance of our genes from our parents is to be governed by the rules of classical mechanics and quantum mechanics must play a role in it.” He hypothesized that quantum mechanics held the key to unraveling the mysteries behind the processes of life and he was right. Johnjoe McFadden (a biologist) and Jim Al Khalili (a nuclear physicist) also believe DNA mutation can be explained by quantum mechanics, specifically quantum tunneling and are conducting experiments to prove it.
Friedrich Hund came across quantum tunneling in 1927 by firing waves at a barrier, predicting that none of them would be able to cross it as classical laws of physics stated particles did not possess enough energy to penetrate the barrier. To his surprise, the particles crossed the barrier. This was later credited to a minute probability that the particles could ‘tunnel’ to the other side the barrier using surrounding energy.
Such particles have wave-like properties enabling them to change position because at the subatomic level, all particles behave like waves as they don’t have a fixed position in space.
These particles act as glue, holding DNA together.
DNA is a double helix made of nucleotides held together by hydrogen bonds. Nucleotides are organic molecules made of a phosphate group, a sugar group and 4 nitrogenous bases. The bases are arranged in specific sequences and glued together by protons. These sequences code for all the proteins that make up living organisms. A change in this code is a mutation. They are most likely to occur during cell division as DNA strands separate in order to replicate themselves. During cell division, if protons in hydrogen atoms change their position, there is a change in the sequence of nitrogenous bases which creates mutant DNA. McFadden and Al Khalili formed a research team at the University of Surrey to find out what causes this change in proton position, the probability of a change in proton position during cell division and if it can lead to cells turning cancerous as a result of mutation.
To understand the causes of mutation, the team investigated the genetic structure of M. tuberculosis, a bacterium that causes tuberculosis.
They discovered that in an environment almost completely lacking oxygen, the bacteria could mutate, becoming more fatal.
This specific mutation seemed to occur at a high frequency as their research continued, defying part of Charles Darwin’s evolution theory which states that although mutations were necessary to increase genetic variation, they should be random and no mutation should be more frequent than another. The experiment concluded that a change in environment could trigger random and frequent mutations.
The next phase in the team’s research is to understand how the mass of hydrogen atoms affect mutations. They intend to do this by comparing behaviors of normal and modified DNA where all hydrogen atoms are be replaced by deuterium (heavier isotope of hydrogen) atoms. They hypothesize that if protons in hydrogen atoms tunnel to positions outside the DNA sequence, the probability and the rate of mutations will be lower in modified DNA as compared to normal DNA because deuterium atoms are heavier and less likely to alter position in modified DNA. However, it is expected to take years to design and conduct the experiments.
Undisputedly, Al Khalili and McFadden aren’t alone in their quest to understand DNA mutation. In the past decade, the evolution of CRISPR has accelerated the rate at which scientists can study DNA and how it mutates.
CRISPR is a technology that can manipulate DNA by editing, inserting or removing sections of DNA sequences.
It inserts strands of RNA into an enzyme which is then transported to a section of DNA with a suitable gene sequence. The enzyme enters the DNA by making cuts on either side of the helix structure, these cuts are repaired by the cell after the enzyme has entered and the genes are modified while the cell heals.
At present, scientists across the globe are using CRISPR to conduct experiments on DNA to observe how it changes at each stage of human life. One such scientist is Kathy Niakan, a biologist specializing in embryonic development at the Francis Crick Institute in the UK. Her team is looking into how DNA changes during embryonic fertilization by using CRISPR to mutate POU5F1, a gene that is paramount to embryonic development, in order to understand how human embryos continue to develop despite changes in DNA. Dieter Egli (a biologist specializing in stem-cells) at Columbia University and Shoukhrat Mitalipov (a biologist specialized in reproduction) at the Oregon Health and Science University are also using CRISPR-Cas 9 to observe embryos made with mutated sperm cells. They are studying sperm cells carrying EYS (a mutated gene that causes blindness) and sperm cells carrying a mutation causing genetic heart conditions and its effects on embryos respectively. CRISPR has enabled scientists like Niakan, Egli and Mitalipov across the globe to study DNA in ways that were unfathomable a decade ago and although research is still in its infancy, its potential is obvious. Scientists are optimistic that when the specific nature of genetic mutation is uncovered, all forms of cancer and genetic disorders can be eradicated once and for all. It’s only a matter of time before the mystery is unveiled.
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References:
https://www.ted.com/talks/jim_al_khalili_how_quantum_biology_might_explain_life_s_biggest_questi ons/discussion https://www.philipball.co.uk/articles/other/108-quantum-biology-an-introduction https://books.google.ae/books?hl=en&lr=&id=KAIB_3kwMbEC&oi=fnd&pg=PT5&dq=info:bJaPyNXg c0EJ:scholar.google.com&ots=rqgr7QD9p6&sig=xDvbOZB7X3cjf-C6kun8BC4_Qh0&redir_esc=y#v =onepage&q&f=false https://www.alphr.com/science/1007203/jim-al-khalili-on-why-quantum-biology-matters-the-payback-i f-it-s-true-is-huge/ https://the-gist.org/2017/02/schrodingers-mutations/ https://www.discovermagazine.com/the-sciences/solving-biologys-mysteries-using-quantum-mechan ics https://scivpro.com/manuscript/10_32386_scivpro_000020/ https://www.scientificamerican.com/article/crispr-gene-editing-in-human-embryos-wreaks-chromosome-m ayhem/ https://www.nature.com/news/uk-scientists-gain-licence-to-edit-genes-in-human-embryos-1.19270
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