Origin of Life

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In ecology we are dealing primarily with the
three starred levels of integration Krebs-What
is Ecology Biosphere. Ecosystems
Communities Populations Organisms
Organ systems Organs
TissuesCells Subcellular
organelles Molecules
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Definition of Life Any entity or set of
entities that can replicate, mutate and be
subject to natural selection. Examples viruses,
bacteria, eukaryotic cells, multicellular
animals, fungi and plants.
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Origin of Life

• A View from the Earth

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Orig Life Evol Biosph. 1998 Oct28(4-6)515-21.
Photosynthesis and the origin of life. Hartman
H. IASB, Berkeley, CA 94707, USA. The origin
and evolution of photosynthesis is considered to
be the key to the origin of life. This eliminates
the need for a soup as the synthesis of the
bioorganics are to come from the fixation of
carbon dioxide and nitrogen. No soup then no RNA
world or Protein world. Cyanobacteria have been
formed by the horizontal transfer of green sulfur
bacterial photoreaction center genes by means of
a plasmid into a purple photosynthetic bacterium.
The fixation of carbon dioxide is considered to
have evolved from a reductive dicarboxylic acid
cycle (Chloroflexus) which was then followed by a
reductive tricarboxylic acid cycle (Chlorobium)
and finally by the reductive pentose phosphate
cycle (Calvin cycle). The origin of life is
considered to have occurred in a hot spring on
the outgassing early earth. 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
biopoesis, 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. Thus the origin
and evolution of the genetic code is a late
development and records the takeover of the clay
by RNA.
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Appl Environ Microbiol. 1994 Dec60(12)4517-26.
Anaerobic oxidation of ferrous iron by purple
bacteria, a new type of phototrophic metabolism.
Ehrenreich A, Widdel F. Max-Planck-Institut fur
Marine Mikrobiologie, Bremen, Germany. Anoxic
iron-rich sediment samples that had been stored
in the light showed development of brown, rusty
patches. Subcultures in defined mineral media
with ferrous iron (10 mmol/liter, mostly
precipitated as FeCO3) yielded enrichments of
anoxygenic phototrophic bacteria which used
ferrous iron as the sole electron donor for
photosynthesis. The existence of ferrous
iron-oxidizing anoxygenic phototrophs may offer
an explanation for the deposition of early
banded-iron formations in an assumed anoxic
biosphere in Archean times.
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The Origin and Evolution of the Genetic Code
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Chem Commun (Camb). 2003 Jun 21(12)1458-9.
Synthesis of 35-40 mers of RNA oligomers from
unblocked monomers. A simple approach to the RNA
world. Huang W, Ferris JP. Department of
Chemistry and New York Center for Studies on the
Origins of Life, Rensselaer Polytechnic
Institute, 110 8th Street, Troy, NY 12180, USA.
RNA oligomers greater than 35-40 mers in length
form in one day in the montmorillonite
clay-catalyzed reaction of unblocked RNA monomers
at 25 degrees C in aqueous solution.
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1 Science. 2003 Oct 24302(5645)618-22. .
Experimental models of primitive cellular
compartments encapsulation, growth, and
division. Hanczyc MM, Fujikawa SM, Szostak JW.
Howard Hughes Medical Institute and Department of
Molecular Biology, Massachusetts General
Hospital, Boston, MA 02114, USA. The clay
montmorillonite is known to catalyze the
polymerization of RNA from activated
ribonucleotides. Here we report that
montmorillonite accelerates the spontaneous
conversion of fatty acid micelles into vesicles.
Clay particles often become encapsulated in these
vesicles, thus providing a pathway for the
prebiotic encapsulation of catalytically active
surfaces within membrane vesicles. In addition,
RNA adsorbed to clay can be encapsulated within
vesicles. Once formed, such vesicles can grow by
incorporating fatty acid supplied as micelles and
can divide without dilution of their contents by
extrusion through small pores. These processes
mediate vesicle replication through cycles of
growth and division. The formation, growth, and
division of the earliest cells may have occurred
in response to similar interactions with mineral
particles and inputs of material and energy.
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Orig Life Evol Biosph. 1998 Oct28(4-6)515-21.
Photosynthesis and the origin of life. Hartman
H. IASB, Berkeley, CA 94707, USA. The origin
and evolution of photosynthesis is considered to
be the key to the origin of life. This eliminates
the need for a soup as the synthesis of the
bioorganics are to come from the fixation of
carbon dioxide and nitrogen. No soup then no RNA
world or Protein world. Cyanobacteria have been
formed by the horizontal transfer of green sulfur
bacterial photoreaction center genes by means of
a plasmid into a purple photosynthetic bacterium.
The fixation of carbon dioxide is considered to
have evolved from a reductive dicarboxylic acid
cycle (Chloroflexus) which was then followed by a
reductive tricarboxylic acid cycle (Chlorobium)
and finally by the reductive pentose phosphate
cycle (Calvin cycle). The origin of life is
considered to have occurred in a hot spring on
the outgassing early earth. 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
biopoesis, 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. Thus the origin
and evolution of the genetic code is a late
development and records the takeover of the clay
by RNA.
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Conclusion
The Clay world evolved up metabolism and the
genetic code.