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Ancient Living Organisms Escaping from, or Imprisoned in, the Vents?
We have recently criticised the natural pH gradient hypothesis which purports to explain how the difference in pH between fluid issuing from ancient alkali vents and the more acidic Hadean ocean could have driven molecular machines that catalyse reactions that are useful in prebiotic and autotrophic...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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MDPI
2017
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617961/ https://www.ncbi.nlm.nih.gov/pubmed/28914790 http://dx.doi.org/10.3390/life7030036 |
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author | Jackson, J. Baz |
author_facet | Jackson, J. Baz |
author_sort | Jackson, J. Baz |
collection | PubMed |
description | We have recently criticised the natural pH gradient hypothesis which purports to explain how the difference in pH between fluid issuing from ancient alkali vents and the more acidic Hadean ocean could have driven molecular machines that catalyse reactions that are useful in prebiotic and autotrophic chemistry. In this article, we temporarily suspend our earlier criticism while we consider difficulties for primitive organisms to have managed their energy supply and to have left the vents and become free-living. We point out that it may have been impossible for organisms to have acquired membrane-located proton (or sodium ion) pumps to replace the natural pH gradient, and independently to have driven essential molecular machines such as the ATP synthase. The volumes of the ocean and of the vent fluids were too large for a membrane-located pump to have generated a significant ion concentration gradient. Our arguments apply to three of the four concurrent models employed by the proponents of the natural pH gradient hypothesis. A fourth model is exempt from these arguments but has other intrinsic difficulties that we briefly consider. We conclude that ancient organisms utilising a natural pH gradient would have been imprisoned in the vents, unable to escape and become free-living. |
format | Online Article Text |
id | pubmed-5617961 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-56179612017-09-29 Ancient Living Organisms Escaping from, or Imprisoned in, the Vents? Jackson, J. Baz Life (Basel) Review We have recently criticised the natural pH gradient hypothesis which purports to explain how the difference in pH between fluid issuing from ancient alkali vents and the more acidic Hadean ocean could have driven molecular machines that catalyse reactions that are useful in prebiotic and autotrophic chemistry. In this article, we temporarily suspend our earlier criticism while we consider difficulties for primitive organisms to have managed their energy supply and to have left the vents and become free-living. We point out that it may have been impossible for organisms to have acquired membrane-located proton (or sodium ion) pumps to replace the natural pH gradient, and independently to have driven essential molecular machines such as the ATP synthase. The volumes of the ocean and of the vent fluids were too large for a membrane-located pump to have generated a significant ion concentration gradient. Our arguments apply to three of the four concurrent models employed by the proponents of the natural pH gradient hypothesis. A fourth model is exempt from these arguments but has other intrinsic difficulties that we briefly consider. We conclude that ancient organisms utilising a natural pH gradient would have been imprisoned in the vents, unable to escape and become free-living. MDPI 2017-09-15 /pmc/articles/PMC5617961/ /pubmed/28914790 http://dx.doi.org/10.3390/life7030036 Text en © 2017 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Review Jackson, J. Baz Ancient Living Organisms Escaping from, or Imprisoned in, the Vents? |
title | Ancient Living Organisms Escaping from, or Imprisoned in, the Vents? |
title_full | Ancient Living Organisms Escaping from, or Imprisoned in, the Vents? |
title_fullStr | Ancient Living Organisms Escaping from, or Imprisoned in, the Vents? |
title_full_unstemmed | Ancient Living Organisms Escaping from, or Imprisoned in, the Vents? |
title_short | Ancient Living Organisms Escaping from, or Imprisoned in, the Vents? |
title_sort | ancient living organisms escaping from, or imprisoned in, the vents? |
topic | Review |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617961/ https://www.ncbi.nlm.nih.gov/pubmed/28914790 http://dx.doi.org/10.3390/life7030036 |
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