Considering that carbon accounts for approximately 9% ( w/ w) of fresh living matter (one liter, L, weighting 1.1 kg), this has −1.6 × 10 3 J K −1 L −1 (−1.61 × 10 4 × 1.1 × 9/100) entropy attributable to biomass standard formation in situ. In fact, the standard entropy of formation of dry glucose, −2.12 × 10 2 J K −1 mol −1 (equivalent to −2.95 × 10 3 J K −1 carbon kg −1), decreases in aqueous solution to −1.16 × 10 3 J K −1 glucose mol −1 (calculated from ), equivalent to −6.44 × 10 3 J K −1 glucose kg −1 or −1.61 × 10 4 J K −1 carbon kg −1. The compartmentation of components, sequences of nucleic acids and proteins, ordered membrane structures, etc., although key to life, has minor contributions to the low relative entropy of the whole organism. Therefore, in addition to chemical biomass, some living features should account for minor contributions to the low entropy of organisms. When referring to one unit of carbon weight, the entropy of formation at room temperature (25–30 ☌) of the dry matter of cells is in the same range as that of glucose and amino acids commonly feeding the growth of cells, approximately 2 × 10 3 J K −1 carbon kg −1, and of the same living cell, and lower than CO 2 gas (4.8 × 10 3 J K −1 carbon kg −1). However, for some specific purposes, they are expressed per carbon atom gram, total mass, volume and, even, energy content or produced involved. Usually, for well-defined chemicals and for reactions, the entropy content and production (respectively) are expressed per mole. Frequently, this refers to the magnitude of entropy produced when the components of the organism are oxidized to CO 2 + H 2O. Sometimes, the low entropy of one macro-structure is related to the entropy of their disassembled molecules. However, the low entropy associated with one organism structure has been approached diversely. Recent theoretical and experimental investigations are uncovering aspects of development, cancer, and biological evolution, the understanding of which benefits from entropy approaches and, furthermore, entropy content and changes determine their occurrence.įor well-defined chemical components, the absolute entropy of formation from their constituting atomic elements (, accessed on 13 March 2022) has become the most common reference. However, a role of entropy per se has barely been assigned in biology. Enzymes and genes are described, whose control minimizes the rate of production of entropy and could explain selective pressures in biological evolution and the rapid proliferation of cancer cells.įor actual values and changes (Δ), respectively, in processes at the absolute temperature T.įree energy and enthalpy have a clear physical significance, which determines the course of biological processes related to equilibrium constants of reactions and energy requirements. The comparatively very low entropy produced in other processes (approximately 4.8 × 10 2 J K −1 L −1 day −1 in the human body) must be rapidly exported outside as heat to preserve low entropy decreases due to compartmentation and non-equilibrium metabolism. The photosynthetic conversion of radiant energy to biomass energy accounts for most entropy (2.8 × 10 5 J K −1 carbon kg −1) produced by living beings. No other living feature contributes significantly to the low entropy associated with life. DNA and proteins do not supply significant decreases in thermodynamic entropy, but their low informational entropy is relevant for life and its evolution. The compartmentation of metabolites and the departure from the equilibrium of metabolic reactions account for reductions in entropy of 1 and 40–50 J K −1 L −1, respectively, and, though small, are distinctive features of living tissues. The absolute entropy of the mixed components of non-living biomass (approximately −1.6 × 10 3 J K −1 L −1) is the reference to which other entropy decreases would be ascribed to life. Attempts to find and quantify the supposed low entropy of organisms and its preservation are revised.
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