Counterintuitive physics property found to be widespread in living organisms

Counterintuitive physics property found to be widespread in living organisms
A negative differential response occurs in substrate inhibition, a process that occurs in about 20% of all known enzymes. Credit: Khopkins2010, Wikimedia Commons

Ever since the late 19th century, physicists have known about a counterintuitive property of some electric circuits called negative resistance. Typically, increasing the voltage in a circuit causes the electric current to increase as well. But under some conditions, increasing the voltage can cause the current to decrease instead. This basically means that pushing harder on the electric charges actually slows them down.

Due to the relationship between current, voltage, and resistance, in these situations the resistance produces power rather than consuming it, resulting in a "negative resistance." Today, negative resistance devices have a wide variety of applications, such as in fluorescent lights and Gunn diodes, which are used in radar guns and automatic door openers, among other devices.

Most known examples of negative resistance occur in human-engineered devices rather than in nature. However, in a new study published in the New Journal of Physics, Gianmaria Falasco and coauthors from the University of Luxembourg have shown that an analogous property called negative differential response is actually a widespread phenomenon that is found in many that occur in living organisms. They identify the property in several vital biochemical processes, such as , DNA replication, and ATP production. It seems that nature has used this property to optimize these processes and make living things operate more efficiently at the molecular scale.

"This counterintuitive, yet common phenomenon has been found in a wealth of physical systems after its first discovery in low-temperature semiconductors," the researchers wrote in their paper. "We have shown that a negative differential response is a widespread phenomenon in chemistry with major consequences on the efficacy of biological and artificial processes."

As the researchers explained, a negative differential response can occur in biochemical systems that are in contact with multiple biochemical reservoirs. Each reservoir tries to pull the system to a different equilibrium point (like a balance point), so that the system is constantly exposed to competing thermodynamic forces.

When a system is in equilibrium with its surroundings, any small perturbation, or noise, affecting the reservoirs will typically cause an increase in the production rate of some product, in accordance with positive entropy. The production rate of a product can be thought of as a chemical current. From this perspective, the increase in noise that causes an increase in chemical current is analogous to the "normal" case in electric circuits in which an increase in voltage causes an increase in .

But when a system in contact with multiple reservoirs becomes out of equilibrium, it may respond differently to noise. In an out-of-equilibrium system, additional factors come into play, so that an increase in noise decreases the chemical current. This negative differential response is analogous to the case in which electric circuits exhibit negative resistance.

In their work, the researchers identified several biological processes that have negative differential responses. One example is substrate inhibition, which is a process used by enzymes to regulate their ability to catalyze chemical reactions. When a single substrate molecule binds to an enzyme, the resulting enzyme-substrate complex decays into a product, generating a chemical current. On the other hand, when the substrate concentration is high, two substrate molecules may bind to an enzyme, and this double binding prevents the enzyme from producing more product. As an increase in substrate molecule concentration causes a decrease in the chemical current, this is a negative differential response.

As a second example, the researchers showed that a negative differential response also occurs in autocatalytic reactions—"self-catalyzing" reactions, or reactions that produce products that catalyze the reaction itself. Autocatalytic reactions occur throughout the body, such as in DNA replication and ATP production during glycolysis. The researchers showed that negative differential responses can arise when two autocatalytic reactions occur simultaneously in the presence of two different chemical concentrations (reservoirs) in an out-of-equilibrium system.

The researchers also identified negative differential responses in dissipative self-assembly, a process in which energy is needed for a system to self-assemble, making it far from equilibrium. Dissipative self-assembly occurs, for example, in the ATP-driven self-assembly of actin filaments—the long, thin microstructures in the cytoplasm of cells that give cells their structure.

Nature does everything for a reason, and the presence of negative differential response in living organisms is no exception. The researchers showed that this property imparts advantages for biochemical processes mainly in terms of energy efficiency. In substrate inhibition, for example, it allows a system to reach homeostasis with less energy than would otherwise be required. In dissipative self-assembly, the negative differential response allows the system to realize a nearly optimal signal-to-noise ratio, ultimately increasing the efficiency of the self-assembly process.


Explore further

Researchers get around bad gap problem with graphene by using negative differential resistance

More information: Gianmaria Falasco et al. "Negative differential response in chemical reactions." New Journal of Physics. DOI: 10.1088/1367-2630/ab28be
Journal information: New Journal of Physics

© 2019 Science X Network

Citation: Counterintuitive physics property found to be widespread in living organisms (2019, August 13) retrieved 20 August 2019 from https://phys.org/news/2019-08-counterintuitive-physics-property-widespread.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
3290 shares

Feedback to editors

User comments

Aug 13, 2019
Nature does everything for a reason, and the presence of negative differential response in living organisms is no exception
One machine's PID is another machine's negative differential response ...

Aug 13, 2019
These scientists call the counterintuitive - property 'self-assembly' - and "self-catalyzing" - almost purposely avoiding the courageous more accurate description NEGENTROPY - even the 'negative resistance' phenomenon- they also describe in biologic reactions- suggest the quasi superconductive in biology (threads of DNA OR gold become superconductive when subjected to lightning / bliss like amperage surges at the moment of crystallization - because of the onset of phase conjugate implosive symmetry) - - ... of course if they DID use the correct term NEGENTROPY- THEN they would have to ask the question - what is THE ORIGIN OF BIOLOGIC NEGENTROPY - (compelling them to read my new book- by that title http://www.fracta...pacetime

oh everything is OK and correct because it is in the nomenclature of mushroom cultivation(squeeze their mind feed them with bullshit, cut what will appear)

Aug 13, 2019
@fractalfield I have no idea what these "quasi superconductive" bits might be (what does that even mean? No, I'm not buying your book to find out), but a drop of entropy -which negative resistance might suggest- is perfectly consistent with the second law of thermodynamics. That's because these enzymes are not dropping entropy out of thin air. The second law only applies to isolated systems.

Systems which exchange energy and entropy with their environment or other external systems *can* drop their own entropy, but they can only do that at the expense of these external bits they interact with, i.e. by exporting their own entropy to them. The entire set of these interacting systems will still see an entropy increase as a whole though.

Aug 13, 2019
suggest the quasi superconductive in biology


All our electrical engineering is based on SOLID STATE components.
Literally solid materials conducting electricity. But liquids and gases conduct electricity differently. Since in liquids and gases the conductor can deform and avoid resistance traffic jams. In Ohms Law for Plasma's, resistance is only about one fifth of the total electric effect in the plasma.

Aug 13, 2019
Life is ultimate engineering. Crazy exact engineering coupled with growth. It's so above our heads still.

Aug 13, 2019
Life is ultimate engineering. Crazy exact engineering coupled with growth. It's so above our heads still.


Life is "just barely good enough" engineering. It's not a designed product; it's stuff thrown together randomly that happens to work. It survived, and none of the other randomly thrown together stuff managed to do so. Later, as the environment changed, it no longer survived, and some other randomly thrown together collection of parts managed to survive.

Aug 14, 2019
Nature does everything for a reason? I cannot agree.

Reasons for doing things are human constructs.

Nature has only facts.

Aug 14, 2019
it's stuff thrown together randomly that happens to work


I'm an atheist, but we still can't even create a (super complex) yeast cell. No one has done this randomly. They've never created biology from pre-biology chemicals ... yet.

It's as if biological life took trillions of years plus to evolve in a near infinite universe, and life on Earth was seeded by Aliens in the Cambrian era. lol

Quick! I think of sea mammals unused hip bone to calm me back down to Darwin.

Aug 14, 2019
The article is confusingly written, there is no such thing as "negative resistance" that "produces power" since that is thermodynamically impossible. Later the article switch to the correct negative *differential* resistance/response and implies "energy is needed", just less.

More to the point, the paper is confusingly written. The biological examples have evolved under the constraint of differential reproduction of a population (species). And even then it is only maximized under selection - thermodynamic efficiency is likely coincidental.

Life is ultimate engineering.


Are you suggesting religious superstition amidst the science?

We know it is not, it is a process, of evolution. Which trivially (according to modern understanding) can produce the appearance of "design". This is Biology 101 stuff!

Aug 14, 2019
Great article, I'm gonna go out on a limb and say ...
"It's all about the proton weights!"

If a proton exchanges an electron weight with a neighbour, there will be an observable EM field reaction because of the two new weights.

The donor will be lighter so it will release some EM weight (Which will be observed as current), equaling the weight of the Electron.

The recipient proton will be an electron weight heavier which will also cause the EM field to flow, this time towards the elemental structure as it builds a new electron weight.

Aug 16, 2019
Life is ultimate engineering. Crazy exact engineering coupled with growth. It's so above our heads still.

I'm having a negative differential response to that.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more