Thermosynthesis is a theoretical mechanism proposed by Anthonie Muller for biological use of the free energy in a temperature gradient to drive energetically uphill

anabolic Anabolism () is the set of metabolic pathways that construct macromolecules like DNA or RNA from smaller units. These reactions require energy, known also as an endergonic process. Anabolism is the building-up aspect of metabolism, whereas catab ...

reactions. It makes use of this thermal gradient, or the dissipative structure of

convection Convection is single or Multiphase flow, multiphase fluid flow that occurs Spontaneous process, spontaneously through the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoy ...

in this gradient, to drive a microscopic

heat engine A heat engine is a system that transfers thermal energy to do mechanical or electrical work. While originally conceived in the context of mechanical energy, the concept of the heat engine has been applied to various other kinds of energy, pa ...

that performs

condensation reaction In organic chemistry, a condensation reaction is a type of chemical reaction in which two molecules are combined to form a single molecule, usually with the loss of a small molecule such as water. If water is lost, the reaction is also known as a ...

s. Thus negative entropy is generated. The components of the biological thermosynthesis machinery concern progenitors of today's

ATP synthase ATP synthase is an enzyme that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi). ATP synthase is a molecular machine. The overall reaction catalyzed ...

, which functions according to the binding change mechanism, driven by

chemiosmosis Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient. An important example is the formation of adenosine triphosphate, adenosine triphosphate (ATP) by the movement of hydrogen ion ...

. Resembling primitive free energy generating physico-chemical processes based on temperature-dependent adsorption to inorganic materials such as

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

, this simple type of energy conversion is proposed to have sustained the

origin of life Abiogenesis is the natural process by which life arises from abiotic component, non-living matter, such as simple organic compounds. The prevailing scientific hypothesis is that the transition from non-living to organism, living entities on ...

, including the emergence of the

RNA World The RNA world is a hypothetical stage in the evolutionary history of life on Earth in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins. The term also refers to the hypothesis that posits the existence ...

. For this RNA World it gives a model that describes the stepwise acquisition of the set of

transfer RNA Transfer ribonucleic acid (tRNA), formerly referred to as soluble ribonucleic acid (sRNA), is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length (in eukaryotes). In a cell, it provides the physical link between the gene ...

s that sustains the

Genetic code Genetic code is a set of rules used by living cell (biology), cells to Translation (biology), translate information encoded within genetic material (DNA or RNA sequences of nucleotide triplets or codons) into proteins. Translation is accomplished ...

. The phylogenetic tree of extant transfer RNAs is consistent with the idea. Thermosynthesis may still occur in some terrestrial and extraterrestrial environments. However, no organisms are known at present that use thermosynthesis as a source of energy, although it is possible that it might occur in extraterrestrial environments where no light is available, such as on the subsurface ocean that may exist on the moon Europa. Thermosynthesis also permits a simple model for the origin of

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

. It has moreover been used to explain the origin of

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

s by

symbiogenesis Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and possibl ...

of benthic sessile thermosynthesizers at

hydrothermal vent Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hot ...

s during the

Snowball Earth The Snowball Earth is a historical geology, geohistorical hypothesis that proposes that during one or more of Earth's greenhouse and icehouse Earth, icehouse climates, the planet's planetary surface, surface became nearly entirely freezing, fr ...

s of the

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of t ...

. Preliminary experiments have started to attempt to isolate thermosynthetic organisms.

Muller's Biothermosynthesis

A Dutch biochemist and physicist Anthonie Muller wrote many papers on thermosynthesis since 1983. He defined thermosynthesis as: "Biological heat engines working on thermal cycling." also as: "Theoretical biological mechanism for free energy gain from thermal cycling, tentatively stated as the energy source for origin of life." The thermosynthesis concept, biological free energy gain from thermal cycling, is combined with the concept of the RNA World. The resulting overall origin of life model suggests new explanations for the emergence of the genetic code and the ribosome. It is proposed that the first protein named pF(1) obtained the energy to support the RNA World by a thermal variation of F(1) ATP synthase's binding change mechanism. It is further proposed that this pF(1) was the single translation product during the emergence of the genetic machinery. During thermal cycling pF(1) condensed many substrates with broad specificity, yielding NTPs and randomly constituted protein and RNA libraries that contained self-replicating RNA. The smallness of pF(1) permitted the emergence of the genetic machinery by selection of RNA that increased the fraction of pF(1)s in the protein library: (1) an amino acids concatenating progenitor of rRNA bound to (2) a chain of 'positional tRNAs' linked by mutual recognition, and yielded a pF(1) (or its main motif); this positional tRNA set gradually evolved to a set of regular tRNAs functioning according to the genetic code, with concomitant emergence of (3) an mRNA coding for pF(1).

References

External links

* *{{Cite arXiv, eprint=physics/0604084, last1=Muller, first1=Anthonie W. J., title=A search for thermosynthesis: Starvation survival in thermally cycled bacteria, year=2006
Thermosynthesis Niches in the Solar System
Detailed description of the process by Dr. Muller himself. Metabolism

Muller's Biothermosynthesis

See also

References

External links