14 Feb 1990
early life on earth
Oparin Haldane Theory
Early life conditions on earth
- Atmospthere mainly composed of ammonia, water vapour, methane, carbon dioxide and nitrogen.
- Little to no oxygen.
- Reducing atmosphere.
Stages of reaching self replication
- Abiotic synthesis of organic monomers.
- Monomers join to form polymers.
- Molecules coalesce into protoionts, droplets with membranes allowing them to maintain distinct internal chemistry.
- Origin of self-replicating molecules.
What happened after?
- As earth cooled, water vapour condensed into oceans and hydrogen was lost in space.
- Oxygen's lack is crucial, it prevents oxidation of early compounds.
- Energy required to form organics was provided by intense UV rays and lightning (young sun, no ozone).
- The early oceans were a solution fo organics, dubbed the primitive soup.
Miller Urey experiment
- Glass apparatus: gases like methane, ammonia and hydrogen.
- Generate electric sparks while boiling water.
- Condense/recirculate the compounds formed.
Results:
| Compound | percentage |
|---|---|
| Glycine | 2.1 |
| Glycolic acid | 1.9 |
| Alanine | 1.7 |
| Lactic acid | 1.6 |
| Formic acid | 4.0 |
- In anhydrous conditions, heat promotes polymerization/condensation by causing extraction of water molecules.
- Even high yields of inorganic pyrophosphates can be synthesized by condensing cyanic acid on hydroxyapatite.
Protocells
- Sperical array of lipids, that's self organized and endogenously ordered.
- Enables selective permeability.
- Examples include coacervates - droplets of charged organic material, proteinoid microspheres - water filled vesicles surrounded by protein boundary, and liposomes - vesicles surrounded by lipid bilayers.
