Notes on the oparin haldane theory and the abiogenesis of protocells.

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.