Table 1.
Top-Down Imperatives of Life Compared to Bottom-Up Electrochemical Tensions and Their Likely Expenditures
| References | |
|---|---|
| Top down | |
| Overall, life requires convection (or advection) for delivery of nutrients and removal of waste. | Open University Course Team, 1993; Russell and Arndt, 2005 |
| While minimizing internal entropy, cells export entropy to the environment through the use of molecular motors or nanoengines. | Leduc, 1911; Westheimer, 1962; Wicken, 1987; Boyer, 1997; Hoffmann, 2012 |
| All life derives from a single ancestor. | Woese et al., 1990; Doolittle, 1999; Harris et al., 2003 |
| All independent life-forms are cellular and compartmentalized with “chemiosmotic” membranes housing ATPases. | Leduc, 1911; Mitchell, 1979a, 1979b; Kell, 1988; Boyer, 1997; Spitzer and Poole, 2009 |
| Gluconeogenesis predates glycolysis. | Say and Fuchs, 2010; Fuchs, 2011 |
| The first bacteria and archaea were autotrophic. | Berg et al., 2010; Fuchs, 2011 |
| All autotrophic organisms use a redox gradient within the bounds of ∼180 mV to 1.2 V. | Thauer et al., 1977; Ducluzeau et al., 2009 |
| The acetyl coenzyme A pathway is the oldest and simplest known. | Fuchs, 1989, 2011; Crabtree, 1997 |
| Redox bifurcation is used to overcome uphill reactions (quinones, flavins, NAD, methanophenazine, Mo and W enzymes). | Herrmann et al., 2008; Nitschke and Russell, 2009; Kaster et al., 2011; Buckel and Thauer, 2013 |
| LUCA enzymes comprise ferredoxins, acetyl-CoA synthase (ACS), carbon monoxide dehydrogenase (CODH), [NiFe]-hydrogenase, hydrogenlyase, and Mo-pterins, all assembled from a “redox protein construction kit.” | Baymann et al., 2003; Nitschke and Russell, 2009; Schoepp-Cothenet et al., 2012; Nitschke et al., 2013 |
| Alkaline conditions support amine, phosphate, thiol, and sugar chemistries as well as general self-assembly and condensations. | ab intra; Mellersh and Smith, 2010; Cafferty et al., 2013 |
| Lost City Methanosarcinales that thrive at pH 9–10 and 70–80°C use H2 and CH4 as fuels and sulfate (or perhaps nitrate) as electron acceptor and produce CO2 and possibly acetate as waste. | Brazelton et al., 2011; Lang et al., 2012 |
| Bottom up | |
| The emergence of life is coupled to convection. | Baross and Hoffman, 1985; Russell et al., 1989, 1994, 2010; Shock, 1992 |
| Submarine alkaline systems resulting from serpentinization during hydrothermal convection are low entropy and feed H2, CH4, and minor NH3 to the ocean floor. | Russell et al., 1989, 1994, 2003, 2013; Nitschke and Russell, 2009, 2013; Simoncini et al., 2011 |
| Submarine alkaline systems produce mounds comprising inorganic compartments. | Russell et al., 1989, 1994; Kelley et al., 2005; Mielke et al., 2010, 2011; McGlynn et al., 2012 |
| All the inorganic elements required for life to emerge are supplied from either ocean or spring. | Russell and Hall, 1997, 2006; Nitschke and Russell, 2009 |
| Inorganic compartments at the margins of submarine mounds may promote reactions between CO2, NO3-, NO2- and FeIII in the ocean and hydrothermal H2 and CH4 | Nitschke and Russell, 2013; Russell et al., 2013 |
| Proton and redox gradients are an inevitable aspect of interfacing an acidulous ocean and alkaline hydrothermal fluid across a spontaneously precipitated inorganic membrane. | Russell et al., 1994; Russell and Hall, 1997, 2006 |
| Electrochemical gradient energy availability (redox+pH) at such springs totals up to ∼1 V. | Russell and Hall, 1997, 2006; Ducluzeau et al., 2009; Nitschke and Russell, 2009; Barge et al., 2014 |
| Alkaline hydrothermal fluids promote certain reductions, aminations, condensations, and polymerizations. | Huber and Wächtershäuser, 1997, 2003 |
| Mo and W presence could enable uphill thermodynamic reactions through redox bifurcation. | Nitschke and Russell, 2009, 2011 |
| The structures of mackinawite and greigite are affine with [FeFe]- and [FeNi]-hydrogenase and ACS and CODH, and of fougèrite to methane monooxygenase. | Morse and Arakaki, 1993; Russell and Hall, 1997, 2006; McGlynn et al., 2009; Nitschke et al., 2013 |
| Thermal gradients drive a convective polymerase chain reaction and the concentration of charged polymers through thermal diffusion. | Braun et al., 2003; Baaske et al., 2007; Mast and Braun, 2010; Mast et al., 2012, 2013 |
| The duration of alkaline springs in steady state is >30,000 years or >1017 μs—presumed time enough to drive disequilibria-driven pathways toward the production of the complex organic molecules required of life's first chemical and mechanical operations? | Ludwig et al., 2011 |