Quantum Biology and DNA.
Key points.
-Theoretical research suggests that quantum effects could drive mutations in human DNA.-The mechanisms involves quantum transfer through quantum tunnelling,
a process that occurs in one quadrillionth of a second.
-Cells have built-in proof reading systems that help prevent these mutations.
It is possible that quantum mechanics could affect us in a personal way.
Theoretical research is beginning to suggest that quantum effects could drive mutations,
in human DNA.
If true, this could change how we understand cancer, genetic disease,
and even the origins of life.
Scientists once thought that biological systems were too warm,
wet and chaotic to experience weird quantum effects like proton tunnelling,
in which the particles wave form spreads out, allowing it to blip across an energy barrier,
that would normally block its passage.
Generally the more heat and chaos around, the smaller the quantum effect.
For many years scientists thought that in the human body,
quantum behaviours would be too small to matter.
When scientists started investigating the messy and complex world of biology,
they are finding quantum mechanics at play, even within our DNA.
This is the new world of quantum biology.
The double helix of DNA is formed by two coiling molecular strands, with bits at the centre,
that connect each other, with one of four different shapes, named with a letter.
T shapes bond to A shapes, and G shapes bond with C,
forming what are known as base pairs.
These little molecular branches connect through weak attractions,
between their hydrogen atoms, which have a single proton and electron.
Sometimes an error occurs and the letters are paired incorrectly.
This mistake is called as point mutation.
Point mutations can add up and cause problems with DNA,
sometimes leading to cancer or other health problems.
Most often the result of mistakes during DNA replication,
point mutations can be caused by x-ray exposure, UV radiation, or anything that excites
atomic particles to move from their orderly places.
For fifty years scientists have debated whether protons switching positions,
between weakly bound strands of DNA, could cause point mutations.
The answer seemed like no.
Many studies have concluded that the intermediate base pair states,
created by proton switching , were too unstable and short lived,
to be replicated in the DNA.
But a new study finds that these states can be frequent and stable,
and the quantum processes may drive their formations.
Scientists modelled proton transfer between hydrogen bonds of the G-C based pair,
in an infinite sea of spring like vibrating particles,
representing the chaotic cellular environment.
Their calculations show that proton transfer through tunnelling can happen very quickly,
for G-C connections, at the centre of a DNA helix.
This happens with in a few hundred femtoseconds.
Such a rate is much faster than our biological time scale.
This switching happens so fast, and so often, that to our DNA,
it ‘appears’ like a proportion of protons , are always visiting their neighbours.
This is the same way that an image on a screen can flash so quickly, it looks still to our eyes.
This super fast switching of protons from one side of the bridge to the other,
means that base pairs are constantly changing between their original form,
and slightly different shape.
These intermediate forms can cause a mismatch during DNA replication,
when the strands are opened, read and copied.
Instead of preventing protons from tunnelling, our biological warmth,
may act as a source of thermal activation, giving protons enough energy,
to pop over to the other side.
Proton transfer through quantum tunnelling is four times more likely,
than predicted by classical physics.
Not only are these occurrences common, but they are also long lived.
Scientists predict that these molecular changes should be stable,
long enough to be replicated, causing a mutation.
According to the scientist’s calculations, point mutation should appear in our DNA,
much more frequently than they do.
The scientist attribute this difference to highly efficient DNA repair mechanisms,
that find and undo the damage.
Our DNA replication machinery includes a ‘proof reading’ ability,
in which mistakes are deducted and corrected.
The ease of proton tunnelling and the longitivtiy of these intermediate states,
might even be relevant to studies on the origin of life, because the rate of early evolution,
is linked to the mutation rate of single stranded RNA.
Though the quantum world might seem weird, it might have played a role, in giving us life.