📌Definition Table

Term	Definition
Abiogenesis	The origin of living organisms from non-living matter.
Primordial Soup Hypothesis	Theory that life began in a warm, shallow ocean rich in organic compounds.
Miller–Urey Experiment	1953 experiment simulating early Earth conditions to test the primordial soup hypothesis.
Polymerization	The chemical process of linking monomers to form polymers.
Fatty Acid	A building block of lipids, important in membrane formation.
Vesicle	A small, membrane-bound compartment that can form spontaneously from lipids.

📌Introduction

The formation of carbon compounds was a key step in the origin of life. Before cells existed, simple molecules like water, methane, ammonia, and hydrogen reacted to produce the organic building blocks of life — amino acids, sugars, lipids, and nucleotides. These compounds then assembled into polymers and eventually into membrane-bound structures, paving the way for the first living cells.

❤️ CAS Link: Organize a science outreach activity where students build models of early Earth and simulate vesicle formation using soap bubbles or oil-in-water emulsions.

📌 Conditions on Early Earth

• Early Earth’s atmosphere likely contained methane, ammonia, hydrogen, and water vapour, but little to no oxygen.
• High energy sources — UV radiation, lightning, volcanic heat — drove chemical reactions.
• Oceans acted as a solvent where compounds could accumulate.
• No ozone layer meant high UV penetration, which could both drive synthesis and degrade molecules.
• These conditions favoured the formation of organic molecules from inorganic gases.

🧠 Examiner Tip: In essays, link atmospheric composition and energy sources to the formation of organic molecules — omitting one loses marks.

📌 Primordial Soup Hypothesis

• Proposed independently by Oparin and Haldane in the 1920s.
• Suggests early oceans formed a “soup” of organic molecules from atmospheric gases.
• Energy from lightning and UV drove the formation of simple organic compounds.
• Molecules accumulated in oceans, providing building blocks for life.
• This set the stage for polymerisation and protocell formation.
• Hypothesis has been tested experimentally with partial success.

🌍 Real-World Connection: Understanding abiogenesis informs astrobiology, guiding the search for life on planets like Mars and moons like Europa.

📌 Miller–Urey Experiment

• Conducted in 1953 to test the primordial soup hypothesis.
• Simulated early Earth atmosphere with methane, ammonia, hydrogen, and water vapour.
• Passed electric sparks to mimic lightning.
• After a week, found amino acids and other simple organic molecules in the apparatus.
• Proved organic compounds can form under abiotic conditions.
• Later research showed early Earth atmosphere may have been less reducing, raising questions about the experiment’s exact relevance.

📌 Assembly into Polymers

• Organic monomers can link to form polymers (proteins, nucleic acids, polysaccharides).
• Polymerisation can occur on mineral surfaces like clay, which act as catalysts.
• Lipids can spontaneously form micelles and vesicles in water.
• Vesicles provide compartmentalisation, protecting reactions from the external environment.
• These membrane-bound structures are possible precursors to the first protocells.
• Fatty acids, more permeable than modern phospholipids, may have formed primitive membranes.

⚗️ IA Tips & Guidance: For a practical link, consider IAs on self-assembly of lipids into micelles/vesicles or polymerization under simulated conditions — easy to model with safe lab analogues.

🌐 EE Focus: A possible EE topic could be comparing pathways for abiotic synthesis of amino acids in different atmospheric models, linking to planetary habitability.

📝 Paper 2: Data Response Tip: If shown the Miller–Urey setup, label the gas mixture, condenser, spark chamber, and collection trap. Always mention the type of molecules produced.