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== 代谢起源:生理学==
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== 代谢起源:生理学==
 
在早期的地球历史中,具有不同起源过程的不同生命形式可能准同时出现。<ref>{{cite journal |last=Davies |first=Paul |date=December 2007 |title=Are Aliens Among Us? |url=http://www.zo.utexas.edu/courses/kalthoff/bio301c/readings/07Davies.pdf |journal=Scientific American |volume=297 |issue=6 |pages=62–69 |doi=10.1038/scientificamerican1207-62 |accessdate=2015-07-16 |quote=...if life does emerge readily under terrestrial conditions, then perhaps it formed many times on our home planet. To pursue this possibility, deserts, lakes and other extreme or isolated environments have been searched for evidence of "alien" life-forms—organisms that would differ fundamentally from known organisms because they arose independently. |bibcode=2007SciAm.297f..62D |url-status=live |archiveurl=https://web.archive.org/web/20160304185832/http://www.zo.utexas.edu/courses/kalthoff/bio301c/readings/07Davies.pdf |archivedate=4 March 2016}}</ref>其他形式可能已经灭绝(通过其不同的生物化学--如假设的生物化学类型--留下了独特的化石)。有人提出:
 
在早期的地球历史中,具有不同起源过程的不同生命形式可能准同时出现。<ref>{{cite journal |last=Davies |first=Paul |date=December 2007 |title=Are Aliens Among Us? |url=http://www.zo.utexas.edu/courses/kalthoff/bio301c/readings/07Davies.pdf |journal=Scientific American |volume=297 |issue=6 |pages=62–69 |doi=10.1038/scientificamerican1207-62 |accessdate=2015-07-16 |quote=...if life does emerge readily under terrestrial conditions, then perhaps it formed many times on our home planet. To pursue this possibility, deserts, lakes and other extreme or isolated environments have been searched for evidence of "alien" life-forms—organisms that would differ fundamentally from known organisms because they arose independently. |bibcode=2007SciAm.297f..62D |url-status=live |archiveurl=https://web.archive.org/web/20160304185832/http://www.zo.utexas.edu/courses/kalthoff/bio301c/readings/07Davies.pdf |archivedate=4 March 2016}}</ref>其他形式可能已经灭绝(通过其不同的生物化学--如假设的生物化学类型--留下了独特的化石)。有人提出:
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The first organisms were self-replicating iron-rich clays which fixed carbon dioxide into oxalic and other dicarboxylic acids. This system of replicating clays and their metabolic phenotype then evolved into the sulfide rich region of the hotspring acquiring the ability to fix nitrogen. Finally phosphate was incorporated into the evolving system which allowed the synthesis of nucleotides and phospholipids. If biosynthesis recapitulates biopoiesis, then the synthesis of amino acids preceded the synthesis of the purine and pyrimidine bases. Furthermore, the polymerization of the amino acid thioesters into polypeptides preceded the directed polymerization of amino acid esters by polynucleotides.
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''The first organisms were self-replicating iron-rich clays which fixed carbon dioxide into oxalic and other dicarboxylic acids. This system of replicating clays and their metabolic phenotype then evolved into the sulfide rich region of the hotspring acquiring the ability to fix nitrogen. Finally phosphate was incorporated into the evolving system which allowed the synthesis of nucleotides and phospholipids. If biosynthesis recapitulates biopoiesis, then the synthesis of amino acids preceded the synthesis of the purine and pyrimidine bases. Furthermore, the polymerization of the amino acid thioesters into polypeptides preceded the directed polymerization of amino acid esters by polynucleotides.''
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最早的生物是自我复制的富铁粘土,它将二氧化碳固定成草酸和其他二羧酸。这种复制粘土及其新陈代谢表型的系统随后进化到富含硫化物的热泉区获得了固氮的能力。最后磷酸盐被纳入进化的系统,使核苷酸和磷脂的合成成为可能。如果说生物合成概括了生物创建,那么氨基酸的合成就先于嘌呤和嘧啶碱基的合成。此外,氨基酸硫酯聚合成多肽,先于多核苷酸定向聚合氨基酸酯。<ref>{{cite journal |last=Hartman |first=Hyman |date=1998 |title=Photosynthesis and the Origin of Life |journal=Origins of Life and Evolution of Biospheres |volume=28 |issue=4–6 |pages=515–521 |bibcode=1998OLEB...28..515H |doi=10.1023/A:1006548904157 |pmid=11536891}}</ref>
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''最早的生物是自我复制的富铁粘土,它将二氧化碳固定成草酸和其他二羧酸。这种复制粘土及其新陈代谢表型的系统随后进化到富含硫化物的热泉区获得了固氮的能力。最后磷酸盐被纳入进化的系统,使核苷酸和磷脂的合成成为可能。如果说生物合成概括了生物创建,那么氨基酸的合成就先于嘌呤和嘧啶碱基的合成。此外,氨基酸硫酯聚合成多肽,先于多核苷酸定向聚合氨基酸酯。<ref>{{cite journal |last=Hartman |first=Hyman |date=1998 |title=Photosynthesis and the Origin of Life |journal=Origins of Life and Evolution of Biospheres |volume=28 |issue=4–6 |pages=515–521 |bibcode=1998OLEB...28..515H |doi=10.1023/A:1006548904157 |pmid=11536891}}</ref>''
 
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... when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life.<ref>{{cite journal |last=Wolchover |first=Natalie |date=22 January 2014 |title=A New Physics Theory of Life |url=https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/ |journal=Quanta Magazine |accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150613052830/https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/ |archivedate=13 June 2015}}</ref><ref>{{cite journal |last=England |first=Jeremy L. |date=28 September 2013 |title=Statistical physics of self-replication |url=http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsrep.pdf |journal=Journal of Chemical Physics|volume=139 |issue=12 |page=121923 |arxiv=1209.1179 |bibcode=2013JChPh.139l1923E |doi=10.1063/1.4818538 |pmid=24089735  |accessdate=2015-06-18 |url-status=live |archiveurl=https://web.archive.org/web/20150604131515/http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsrep.pdf |archivedate=4 June 2015|hdl=1721.1/90392}}</ref>
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''... when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life.<ref>{{cite journal |last=Wolchover |first=Natalie |date=22 January 2014 |title=A New Physics Theory of Life |url=https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/ |journal=Quanta Magazine |accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150613052830/https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/ |archivedate=13 June 2015}}</ref><ref>{{cite journal |last=England |first=Jeremy L. |date=28 September 2013 |title=Statistical physics of self-replication |url=http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsrep.pdf |journal=Journal of Chemical Physics|volume=139 |issue=12 |page=121923 |arxiv=1209.1179 |bibcode=2013JChPh.139l1923E |doi=10.1063/1.4818538 |pmid=24089735  |accessdate=2015-06-18 |url-status=live |archiveurl=https://web.archive.org/web/20150604131515/http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsrep.pdf |archivedate=4 June 2015|hdl=1721.1/90392}}</ref>''
  ...当一组原子受到外部能量源(如太阳或化学燃料)的驱动,并被热浴(如海洋或大气层)所包围时,它往往会逐渐重组自己,以耗散越来越多的能量。这可能意味着,在某些条件下,物质不可避免地获得了与生命相关的关键物理属性。
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''...当一组原子受到外部能量源(如太阳或化学燃料)的驱动,并被热浴(如海洋或大气层)所包围时,它往往会逐渐重组自己,以耗散越来越多的能量。这可能意味着,在某些条件下,物质不可避免地获得了与生命相关的关键物理属性。''
 
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Orgel总结他的分析说,
 
Orgel总结他的分析说,
 
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There is at present no reason to expect that multistep cycles such as the reductive citric acid cycle will self-organize on the surface of FeS/FeS<sub>2</sub> or some other mineral."<ref>{{cite journal |last=Orgel |first=Leslie E. |date=7 November 2000 |title=Self-organizing biochemical cycles |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=97 |issue=23 |pages=12503–12507 |bibcode=2000PNAS...9712503O |doi=10.1073/pnas.220406697|pmc=18793 |pmid=11058157}}</ref>
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''There is at present no reason to expect that multistep cycles such as the reductive citric acid cycle will self-organize on the surface of FeS/FeS<sub>2</sub> or some other mineral."<ref>{{cite journal |last=Orgel |first=Leslie E. |date=7 November 2000 |title=Self-organizing biochemical cycles |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=97 |issue=23 |pages=12503–12507 |bibcode=2000PNAS...9712503O |doi=10.1073/pnas.220406697|pmc=18793 |pmid=11058157}}</ref>''
 
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目前没有理由期望多步循环,如还原性柠檬酸循环会在FeS/ FeS<sub>2</sub>或一些其他矿物的表面自组织。"
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''目前没有理由期望多步循环,如还原性柠檬酸循环会在FeS/ FeS<sub>2</sub>或一些其他矿物的表面自组织。''
 
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地球化学重建表明,有利于细胞起源的离子成分不可能存在于我们今天所说的海洋环境中,而是与我们今天所说的内陆地热系统的蒸汽主导区的排放相符合。在缺氧的、以二氧化碳为主的原始大气下,地热场附近的水凝结物和蒸发物的化学性质会类似于现代细胞的内环境。因此,细胞前的进化阶段可能发生在浅层的"达尔文池塘"中,池塘内衬与金属硫化物混合的多孔硅酸盐矿物,富含K<sup>+</sup>, Zn<sup>2+</sup>和磷化合物。<ref>{{cite journal |last1=Mulkidjanian |first1=Armen Y. |last2=Bychkov |first2=Andrew Yu. |last3=Dibrova |first3=Daria V. |last4=Galperin |first4=Michael Y. |last5=Koonin |first5=Eugene V. |display-authors=3 |date=3 April 2012 |title=Origin of first cells at terrestrial, anoxic geothermal fields |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=109 |issue=14 |pages=E821–E830 |bibcode=2012PNAS..109E.821M |doi=10.1073/pnas.1117774109  |pmc=3325685 |pmid=22331915}}</ref><ref>Lankenau, Dirk-Henner (2011). "Two RNA Worlds: Toward the Origin of Replication, Genes, Recombination and Repair". In Egel, Richard; Lankenau, Dirk-Henner; Mulkidjanian, Armen Y. (eds.). Origins of Life: The Primal Self-Organization. Heidelberg: Springer. doi:10.1007/978-3-642-21625-1. ISBN 978-3-642-21624-4. LCCN 2011935879. OCLC 733245537.</ref><ref>{{cite journal |last1=Davidovich |first1=Chen |last2=Belousoff |first2=Matthew |last3=Bashan |first3=Anat |last4=Yonath |first4=Ada |date=September 2009 |title=The evolving ribosome: from non-coded peptide bond formation to sophisticated translation machinery |journal=Research in Microbiology |volume=160 |issue=7 |pages=487–492 |doi=10.1016/j.resmic.2009.07.004 |pmid=19619641}}</ref>
 
地球化学重建表明,有利于细胞起源的离子成分不可能存在于我们今天所说的海洋环境中,而是与我们今天所说的内陆地热系统的蒸汽主导区的排放相符合。在缺氧的、以二氧化碳为主的原始大气下,地热场附近的水凝结物和蒸发物的化学性质会类似于现代细胞的内环境。因此,细胞前的进化阶段可能发生在浅层的"达尔文池塘"中,池塘内衬与金属硫化物混合的多孔硅酸盐矿物,富含K<sup>+</sup>, Zn<sup>2+</sup>和磷化合物。<ref>{{cite journal |last1=Mulkidjanian |first1=Armen Y. |last2=Bychkov |first2=Andrew Yu. |last3=Dibrova |first3=Daria V. |last4=Galperin |first4=Michael Y. |last5=Koonin |first5=Eugene V. |display-authors=3 |date=3 April 2012 |title=Origin of first cells at terrestrial, anoxic geothermal fields |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=109 |issue=14 |pages=E821–E830 |bibcode=2012PNAS..109E.821M |doi=10.1073/pnas.1117774109  |pmc=3325685 |pmid=22331915}}</ref><ref>Lankenau, Dirk-Henner (2011). "Two RNA Worlds: Toward the Origin of Replication, Genes, Recombination and Repair". In Egel, Richard; Lankenau, Dirk-Henner; Mulkidjanian, Armen Y. (eds.). Origins of Life: The Primal Self-Organization. Heidelberg: Springer. doi:10.1007/978-3-642-21625-1. ISBN 978-3-642-21624-4. LCCN 2011935879. OCLC 733245537.</ref><ref>{{cite journal |last1=Davidovich |first1=Chen |last2=Belousoff |first2=Matthew |last3=Bashan |first3=Anat |last4=Yonath |first4=Ada |date=September 2009 |title=The evolving ribosome: from non-coded peptide bond formation to sophisticated translation machinery |journal=Research in Microbiology |volume=160 |issue=7 |pages=487–492 |doi=10.1016/j.resmic.2009.07.004 |pmid=19619641}}</ref>
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==其他非生物起源的情景==
 
==其他非生物起源的情景==
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