(ORDO NEWS) — DNA is known to mutate regularly, for better or worse, causing both evolution and disease. Researchers at the University of Surrey have found evidence that some of these spontaneous mutations may be caused by a strange and little-studied area of quantum mechanics.
DNA gets its famous double helix shape from molecules called bases that are joined by hydrogen bonds. These bases, denoted by the letters A, C, T, and G, usually follow strict rules about how they connect – A bonds to T, and C bonds to G.
But sometimes these hydrogen bonds can be changed, that is, bases can form pairs with the wrong partner. This causes point mutations in DNA that are mostly harmless but can sometimes lead to genetic disorders.
In a new study, the Surrey scientists found that some of these modifications could be the result of a strange phenomenon in quantum physics known as quantum tunneling. It sounds like science fiction to us in the world of classical physics, but sometimes particles can spontaneously tunnel through barriers they shouldn’t have the energy to overcome.
What is quantum tunneling
Think of it like a ball in a valley. Classical physics says that to get this ball to the other side of the hill, it takes a certain amount of energy to push it up and over the hill.
But quantum physics can allow this ball (i.e. particle) to suddenly “tunnel” through the hill of its own accord and appear almost instantly on the other side. Again, it sounds incredible, but quantum tunneling is a well-documented phenomenon that occurs in a number of scenarios such as nuclear fusion.
In the case of DNA mutations, the team says the tunneling particles are protons inside hydrogen atoms that can jump from one side of the bond to the other. If they happen to do this just before the two strands of DNA are cleaved in the process of cell replication, the protons can get stuck on the wrong side, leading to DNA mismatch and potential mutation.
The idea that this could happen by mutating DNA was first put forward decades ago, but the mechanism has since been largely ignored. This is because the biological environment has long been considered too warm and difficult for quantum tunneling.
But in the new study , the team found that not only does this happen in the bio-environment, but the biogenic heat itself actually activates protons to make the jump.
The team used a process called open quantum systems to model the dynamics of the process and showed that these protons hop back and forth more often than previously thought. This suggests that proton transfer by quantum tunneling plays a more important role in genetic mutations than is commonly believed.
“Biologists generally expect tunneling to play a significant role only at low temperatures and in relatively simple systems,” explained Dr. Marco Sacchi, co-author of the study. “So they tend to ignore quantum effects in DNA. We believe that in our study, we have proven that these assumptions are incorrect.”
The team says that if the model proves correct, it could have a wide impact on existing models of genetic mutations.
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