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Murray Edwards College
University of Cambridge

School Winner: The Quantum World

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    23 Jul

    3C Alice Turnock photoWinning Entry George AbbotSince listening to Johnjoe McFadden and Jim Al-Khalili discuss their book ‘Life on the Edge: The Coming of Age of Quantum Biology’ at Surrey University last October, I’ve been immensely fascinated by the way that quantum mechanics, despite only affecting the very small, can underpin science and even explain how our bodies work. In the early twentieth century, scientists were thrown, for they had thought they understood physics. The laws of quantum mechanics don’t obey Newtonian laws, therefore many were sceptical of this new field. Despite still lacking understanding of the mechanisms of quantum mechanics today, it has now been suggested that events on the quantum scale can have wider implications on the observable universe. Whilst the field of quantum biology may sound unfamiliar, it was first established by Per-Olov Löwdin in 1963, who suggested that mutations in DNA may be explained by quantum tunnelling. DNA’s double helix is held together by hydrogen bonds between base pairs on nucleotides. As a hydrogen atom joins the two strands of DNA, it can determine whether or not a gene mutates. Furthermore, a singular hydrogen atom is vulnerable to quantum weirdness, due to its small size. Löwdin proposed that, as the hydrogen atom is normally situated closer to one nucleotide than another, mutations may occur when the hydrogen atom moves by quantum tunnelling to be situated closer to the other nucleotide, and therefore be ‘wrongly’ positioned. Mcfadden and Al-Khalili developed this idea using the superposition principle. This would suggest that before being observed, the hydrogen atom would be in both positions at the same point in time (thus mutated and not mutated). In the presence of an observer, the hydrogen atom would take up a localised position, and a mutation would occur if this was closer to the ‘wrong’ nucleotide.

    Whilst undoubtedly perplexing, quantum tunnelling is perhaps best described with an analogy. If you were to kick a ball up a steep hill, you would expect it to reach a point below the peak of the hill before rolling back down. Quantum tunnelling suggests that the ball would instead be able to ‘tunnel’ through the hill, ending up on the opposite side.

    Understanding genetic mutations would allow us to prevent and control them. Mcfadden and Al-Khalili are in the process of testing their theory, and have deliberated experiments that involve the comparison of regular DNA against modified DNA, where hydrogen atoms are replaced with deuterium atoms. If their theory on genetic mutation is correct, then the modified DNA would mutate significantly less than regular DNA, for the deuterium would be much less likely to move by quantum tunnelling due to its greater size. Whilst the results of the experiments are far away, the possibility of such a medical advance is hugely exciting. 4 in 10 people in the UK will be diagnosed with cancer over their lifetime, and there were around 162,000 deaths from cancer in 2012. Being able to understand quantum tunnelling in relation to genetic mutation has the potential to save millions of lives, and assist greatly in medical progression in helping to treat cancer. “If quantum mechanics hasn’t profoundly shocked you, you haven’t understood it yet” (Bohr), as we continue to be shocked by the quantum world, we will continue to develop understanding of more aspects of life.

    Alice Turnock
    Year 12, George Abbot School
    My name is Alice Turnock and I study chemistry, biology, mathematics and English literature at George Abbot school in Guidlford. I am hoping to study medicine next year and writing a blog entry allowed me to research and explore a concept this is extremely relevant.  In my spare time I enjoy reading and spending time with friends.