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Origin of life
From:http://www.mediafire.com/?jfijmimctnd
And they are permeable to small organic molecules…
…meaning no complex proteins are required to get stuff in.
When a vesicle encounters free fatty acids in solution, it will incorporate them.
Eating and growth are driven purely by thermodynamics.
So far, with naturally occurring simple fatty acids,
we have a vesicle that can spontaneously grow and divide.
The pre-biotic environment contained hundreds of types of different
nucleotides (not just DNA and RNA).
(All it took was 1 to self polymerize.)
Recent experiments have shown that some of these are capable
of spontaneous polymerization, such as Phosphoramidate DNA.
Monomers will base pair with a single stranded template and self ligate.
Hydrogen BondsBase Pair
Covalent BondLigation
They can also polymerize in solution, and spontaneously form new templates, or
extend existing templates.
No special sequences are required, it’s just chemistry.
So far we have lipid vesicles that can grow and divide,
and nucleotide polymers that can self replicate, all on their own.
But how does it become life?
… such as those set up by hydrothermal vents.
(fatty acid vesicles are stable under near boiling conditions)
The high temperatures will separate the polymer strands and increase the
membrane’s permeability to monomers.
The polymer, due to surrounding ions, will increase the osmotic pressure within the
vesicle, stretching its membrane.
A vesicle with more polymer, through simple thermodynamics, will “steal” lipids
from a vesicle with less polymer.
A vesicle that contains a polymer that can replicate faster,
will grow and divide faster,
eventually dominating the population.
-Monomers spontaneously polymerize and copy any template-Heat separates strands, increases membrane permeability to monomers-Polymer backbones attract ions increasing osmotic pressure-Pressure on the membrane drives its growth at the expense of nearby vesicles containing less polymer
Let’s Review: -Monomers diffuse into a fatty acid vesicle
-Mechanical forces cause vesicles to divide-Daughter vesicles inherit polymers from the parent vesicle-Polymer sequences that replicate faster will dominate the population…
Let’s Review: -Vesicles grow into tubular structures
Thus beginning evolution!
It was their ability to spontaneously replicate, irrespective of sequence,
that drove growth and division of the fatty acid vesicles.
Early beneficial mutations would include:
Change sequence to contain only the most common nucleotides.
Early beneficial mutations would include:
Form secondary structures that show some enzymatic activity.
Early polymer enzymes would:
Use high energy molecules in the environment (near thermal vents)
to recharge monomers.