Biological complexity: electric spark of life (Introduction)

by David Turell , Saturday, July 04, 2020, 19:02 (1603 days ago) @ David Turell

Electrons are a vital part of biological processes:

http://nautil.us/issue/86/energy/uncovering-the-spark-of-life

"...humans didn’t invent electricity, no matter how much we’d like to think so. It precedes us, and life itself, as an inanimate physical process. It is also at the core of how organisms access the motivating force for life—energy.

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"Energy is a measure of the ability to do work, and cells, the fundamental unit of life as we know it, have much work to do. They construct proteins, copy themselves, and move against the ubiquitous pull of gravity. In the biosphere we’re familiar with, organisms depend upon the sun to bankroll their work—either directly through photosynthesis, or by consuming its organic products. Both of these processes are fundamentally electrical. So is the metabolism of the deep biosphere, a parallel world beneath our feet1 that thrives in the dark. Thousands of meters down, scientists have found bacteria that electrify themselves by eating and breathing simple geofuels.

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"On Earth’s surface, many organisms produce electricity by shuttling charge from glucose to oxygen. Underground, they can use hydrogen and carbon dioxide. But the operation that generates electricity in both cases is the same—an equilibration of charge between two compatible compounds. After all, electricity is nothing more than energy derived from either static or dynamic charge. But what exactly is charge, and how does life use electricity to do work?

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"The difference in charge between the two terminals is known as voltage, and the flow of current between them can be used productively. On Earth, more ancient, deep biosphere bacteria utilize low voltage circuits, while the more complex surface-dwelling organisms depend upon higher voltages.

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"All cells that have been studied bridge the charge difference between what is eaten and what is breathed with a biological wire known as the electron transport chain (ETC). The universality of the ETC suggests it was an early innovation in the evolution of life on Earth

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"All kinds of compounds, everything from hydrogen gas to sulfate—can serve as the terminals of a metabolic circuit. Despite this flexibility, the depth of structural and functional similarity in the ETC across a multitude of life forms suggests only a few degrees of freedom during the system’s evolution.

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"Annette Rowe is head of the Electromicrobiology Laboratory at the University of Cincinnati, where she studies the often unusual ways that organisms power their metabolic circuits. Some of her research has focused on bacteria capable of breathing current carried by electrodes.2 Reached by phone, Rowe points out that while the metabolic systems of two organisms may “have protein architecture that looks really similar, most of them are uniquely derived, evolutionarily speaking.” This means that the same solution to the problem of distributing the electric harvest throughout the cell has appeared over and over again throughout history. The name of that solution? Adenosine triphosphate.

"Adenosine triphosphate, ATP for short, is one of those incredible pieces of biology that appears to be universal. There is no exception to the rule that to live is to work, and no exception to the rule that all known cells use electrochemical gradients to do work. But most internal cellular processes do not access electricity directly. Instead, they channel the electric power into a mobile intermediary—ATP—for much the same reason that we prefer wireless technology. Dragging a cord about is prohibitively restrictive. Internal cellular processes like active transport, polymerization, and locomotion occur far from metabolic machinery. Instead of depending on a tangle of wires, cells use diffusible ATP to provide the necessary kick. “ATP is a fundamental currency to life as we know it,”

Comment: Extracted from an essay on how to find life on Mars. It appears that are strict rules in evolution to handle the energy electrons provide with ATP used everywhere. Electrons play an integral role in photosynthesis (2020-06-16, 22:31) These are highly complex processes that must be designed