Can quantum mechanics – a field once derided by Albert Einstein as “scary” – affect us in a very personal way? Very likely. Theoretical research is beginning to suggest that quantitative effects can lead to mutations in human DNA. If true, this could change how we understand cancer, genetic diseases, and even the origins of life.
Scientists once thought biological systems were too warm, humid, and chaotic to experience strange quantum effects like proton tunneling, in which a particle’s waveform propagates, allowing it to pass through the energy barrier that normally blocks its passage. In general, the higher the heat and chaos, the lower the quantum effect; Therefore, for many years, scientists believed that quantitative behaviors in the human body would be too small to matter.
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But you cannot find what you are not looking for. When quantum physicists begin to squeeze into the chaotic and complex world of biology, they find quantum mechanics playing a role, even within our DNA. Welcome to the world Quantum biology.
A primer on point mutations
The iconic DNA double helix consists of two coiled molecular strands with bits in the center that connect like puzzle pieces, each with one of four different shapes, named with a letter. T shapes connect to A shapes, and G shapes connect to C shapes, forming what are known as “base pairs”. These small molecular branches are connected by weak attractions between hydrogen atoms, which have one proton and one electron.
Sometimes, something goes wrong and the characters are paired incorrectly – an error we call a point mutation. Point mutations can build up and cause problems with DNA, sometimes leading to cancer or other health problems. Often the result of errors during DNA replication, point mutations can also occur due to exposure to X-rays, ultraviolet light, or anything that excites atomic particles to move from their organized places.
For 50 years, researchers have debated whether switching protons between weakly linked DNA strands can cause point mutations. The answer seemed like no. Several studies concluded that the intermediate base pair states resulting from the proton switch were too unstable and short-lived to be replicated in DNA. But the New study Published in the magazine Communication Physics He found that these states can be repetitive and stable, and that quantum processes may drive their formation.
The researchers modeled proton transport between the hydrogen bonds of the G:C base pair in an endless sea of spring-like vibrational particles, which accounts for the chaotic cellular environment. Their calculations show that the transfer of a proton through quantum tunneling can occur very quickly for the G:C junctions at the center of the DNA helix – within a few hundred femtoseconds, or 0.000000000000001 seconds. This rate is much faster than our biological schedule.
This transformation happens very quickly and often to our DNA, it “looks” as if a percentage of protons are always visiting their neighbors, in the same way that an image on a screen can flash at a speed that seems constant to our eyes. This ultra-fast shift of the protons from one side of the bridge to the other means that the base pairs are constantly changing between their original shape and their slightly different shape. These intermediate forms can cause mismatches during DNA replication, when the strands are opened, read and transcribed.
Rather than blocking the protons from tunneling, our biological warmth may act as a source of thermal activation, giving the protons enough energy to travel to the other side. In fact, the transfer of a proton through quantum tunneling is four times more than what was predicted by classical physics. Not only are these accidents common, but they are also long-lived. Building on previous computational studies, the researchers speculate that these molecular changes must be stable long enough for their recurrence—causing the mutation.
There are two basic limitations with work. First, the researchers did not investigate A:T base pairs, indicating that for these bonds the intermediate state is very unstable and is not likely to play a role in DNA mutations. Second, this theoretical work will make use of empirical tests to validate or challenge results.
How much solace?
Based on the team’s calculations, point mutations in our DNA should appear more frequently than they do. Researchers attribute this difference to “highly efficient DNA repair mechanisms” that detect and disrupt damage. For example, our DNA cloning machinery includes a “proofreading” capability, where errors are caught and corrected – kind of like a typo. Thank goodness for the biological copy editors.
The ease of proton tunneling and the longevity of these intermediate states may be relevant to studies on the origin of life, because the rate of early evolution is related to the mutation rate of single-stranded RNA, the researchers wrote. Thus, although the quantum world may seem strange and distant, it may have played a role in giving us life – and also in taking it away.