Origin of life: Did life begin as chemical gardens?
|January 19, 2016||Posted by News under News, Origin Of Life|
From Tim Requarth at Aeon,
But within modern organisms there is another clue to life’s origins, one that is more obscure than DNA but just as universal – the way cells harvest energy by shuffling around electrically charged molecules. This process goes by the mouthful ‘chemiosmosis’, and was first proposed in 1961 by the eccentric British biochemist Peter Mitchell. Chemiosmosis lacks the coded rigour of DNA, but that primal messiness might be exactly what makes it so revealing.
Energy, Russell thinks, must have preceded anything resembling DNA or RNA, so the origin of chemiosmosis could help to reveal how the first organisms arose. Chemiosmosis takes place deep in our body’s cells, most of which harbour hundreds or thousands of microscopic structures called mitochondria. The mitochondria extract the chemical energy from food and, with the help of the oxygen we breathe, convert it into a molecule called adenosine triphosphate (ATP). Just as much as DNA, ATP is the molecule of life; it is the currency we spend to grow, move or think. Every second, each of our body’s 40 trillion cells use around 10 million molecules of ATP. We can turn over our entire body weight in this special substance every day.
The flow of energy across the membranes of the mitochondria occurs through a molecular Rube Goldberg contraption so elaborate it almost defies comprehension. A chain of dozens of proteins, each consisting of thousands of atoms, traps high-energy electrons (derived from food), and passes them down the chain like a bucket brigade. The movement of electrons through the proteins in the chain creates an electrical current, which is used to trap massive numbers of protons between the mitochondrion’s inner and outer membranes. The only escape for the protons is through another remarkable protein called ATP synthase. It is an engineering miracle, a nanomachine complete with a molecular rotor, stator and driveshaft, which, as protons fall through it, spins like a waterwheel – hundreds of times per second – to produce ATP.
No replication-focused origin-of-life theory has yet provided good explanation for the parallel origin of the elaborate machinery of chemiosmosis. More.
The “chemical garden hypothesis” seems to be a variant of the hydrothermic vents hypothesis.
It goes on. It ends:
Russell’s conception of our species, along with every other living thing, as mere energy patterns, ultimately born of rogue fluctuations in the Universe’s infancy, might make us feel a little less special. Then again, it might also make us feel a little less alone. We are descendants of an unbroken energetic lineage from the dawn of time. Darwin intuited this deep link between biology and physics, speculating that it is ‘probable that the principle of life will hereafter be shown to be part, or consequence, of some general law’. And, he might have added, there’s grandeur in this view of life, too.
It’s interesting but here’s a tip: Whenever the article ends by quoting Darwin and emphasizing our nothingness, one can assume that they don’t have the answer. If they did, they just wouldn’t be talking that way.
See also: Origin of life: Could it all have come together in one very special place?
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