2.1 Origin of Cells

Alexander Oparin and JBS Haldane steps for how life originated

1. Formation of simple organic molecules from inorganic compounds

2. Assembly of carbon compounds into polymers

3. Formation of a polymer that can self-replicate

4. Packaging of molecules into compartments with an internal chemistry different from its surroundings 

Early Earth’s atmosphere

• water vapour

• high levels of co2

• methane

• amonia

• hydrogen sulfide

• hydrogen

Miller and Harold Urey 

Recreated early earth’s atmosphere in a closed system:

• low oxygen levels

• high radiation

• high temperatures

• sparks (lightning storms)

• water vapour, ammonia, methane hydrogen

Result of Miller and Harold Urey experiment

• Long hydrocarbon chains

• 15 of 20 amino acids

Issues with Miller and Harold Urey’s experiment

• no definitive evidence of compounds on earth’s atmosphere

• some theorised hydrocarbons were brought to Earth by meterorites

• Methane and ammonia would not be present

• absence of gases creates a non-reducing environment meaning carbon atoms can’t be formed

• proteins break down in water based environment